Guide to developing and maintaining an effective hearing conservation program

A Guide to
Developing and Maintaining
an Effective Hearing
Conservation Program
Julia and Larry Royster
Sydney Cheryl Sutton
Editor
N. C. Department of Labor
Division of Occupational Safety and Health
1101 Mail Service Center
Raleigh, NC 27699- 1101
Cherie K. Berry
Commissioner of Labor
Acknowledgments
This industry guide was prepared for the North Carolina Department of Labor by Julia
and Larry Royster. Julia Doswell Royster, Ph. D., CCC- A/ SLP, is President of
Environmental Noise Consultants, Inc., of Raleigh, North Carolina ( email:
effective_ hcps@ compuserve. com). Larry H. Royster, Ph. D., is a professor in the
Department of Mechanical and Aerospace Engineering, North Carolina State
University, Raleigh, North Carolina. Mr. Royster wrote the original North Carolina
OSHA noise guidelines and Noise Compliance Plan. Numerous publications have
reported the research of both authors ( see References in this publication). Each author
is recognized as an expert in the areas of noise control and hearing conservation.
Most of the illustrations for this publication were prepared by the E- A- R Division of
Aearo Company. The Aearo Company has granted permission for the use of the illus-trations
in this industry guide.
This guide is intended to be consistent with all existing OSHA standards; there-fore,
if an area is considered by the reader to be inconsistent with a standard,
then the OSHA standard should be followed.
To obtain additional copies of this book, or if you have ques-tions
about N. C. occupational safety and health standards
or rules, please contact:
N. C. Department of Labor
Bureau of Education, Training and Technical Assistance
1101 Mail Service Center
Raleigh, NC 27699- 1101
Phone: ( 919) 807- 2875 or 1- 800- NC- LABOR
____________________
Additional sources of information are listed
on the inside back cover of this book.
____________________
The projected cost of the OSHNC program for federal fiscal year 2002– 2003 is $ 13,130,589.
Federal funding provides approximately 37 percent ($ 4,920,000) of this total.
Printed 7/ 98, 3M
N. C. Department of Labor
Occupational Safety and Health Program
Cherie K. Berry
Commissioner of Labor
OSHA State Plan Designee
Allen McNeely
Deputy Commissioner for Safety and Health
Kevin Beauregard
Assistant Deputy Commissioner for Safety and Health
Contents
Part Page
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1ivi
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1vii
1 Effective Hearing Conservation Programs
( HCPs): Benefits and Strategies . . . . . . . . . . iiv1
A Look at HCPs Nationwide . . . . . . . . . . . . . iiv1
Benefits of the HCP to the Employee . . . iiv3
Benefits of the HCP to the Employer . . . iiv3
2 Organizing Your HCP: Five Phases under
a Key Individual . . . . . . . . . . . . . . . . . . . . . . . . . . . . iiv5
Five Related Phases . . . . . . . . . . . . . . . . . . . . . . iiv5
Characteristics of Effective HCPs . . . . . . . iiv9
Personnel Involved in the HCP . . . . . . . . . . ii10
External Influences on the HCP . . . . . . . . . ii11
Organization Makes the Difference . . . . . ii12
Checklist for HCP Development . . . . . . . . . ii12
3 Education and Motivation. . . . . . . . . . . . . . . . . . . ii13
Education Paves the Way for
Other Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii13
Making Education a Priority. . . . . . . . . . . . . ii14
Developing Adequate Personnel
Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii14
Organizing Sessions for Best Results . . . ii14
A Relevant Approach to Education. . . . . . ii15
Tailoring the Presentation to the
Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii18
Taking Advantage of Motivational
Opportunities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii19
Questions and Suggestions. . . . . . . . . . . . . . . ii19
Checklist for Education and
Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii20
iii
4 Sound Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii21
Types of Surveys and
Instrumentation. . . . . . . . . . . . . . . . . . . . . . . . . . ii21
Ways Sound Survey Results Are Used . . . ii22
Keeping Surveys in Perspective . . . . . . . . . ii22
Planning and Coordinating with
Production Personnel . . . . . . . . . . . . . . . . . . . . ii23
Data Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii24
Employee Participation Is Essential . . . . ii25
Report Preparation. . . . . . . . . . . . . . . . . . . . . . . . ii26
Communicating Exposure Results . . . . . . ii27
Checklist for Sound Surveys . . . . . . . . . . . . . ii27
5 Engineering and Administrative Noise
Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii28
Engineering Controls . . . . . . . . . . . . . . . . . . . . . ii28
Administrative Controls . . . . . . . . . . . . . . . . . . ii33
Solving Noise Control Problems
Using In- House Personnel . . . . . . . . . . . . . . ii36
Sources of Information. . . . . . . . . . . . . . . . . . . . ii37
Checklist for Noise Controls . . . . . . . . . . . . . ii38
6 Hearing Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . ii39
Organizing the HPD Phase for
Success . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii39
Types of HPDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii40
Hearing Protector Attenuation . . . . . . . . . . ii41
Real- World Attenuation . . . . . . . . . . . . . . . . . . ii43
Purchasing Appropriate HPDs . . . . . . . . . . ii44
Maximizing the Effectiveness of HPDs
in Actual Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii47
Motivating Employees to Wear HPDs
Effectively. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii49
Demonstrating Management Support . . ii50
Checklist for Hearing Protection . . . . . . . . ii52
iv
7 Audiometric Evaluations . . . . . . . . . . . . . . . . . . . . ii53
Management Support Needed for
Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii53
Quality Control Responsibilities of
Audiometric Technicians . . . . . . . . . . . . . . . . ii58
Scheduling Audiograms . . . . . . . . . . . . . . . . . . ii60
Using the Audiogram Session to Best
Advantage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii61
Following up on Audiometric Results . . . ii62
Educating Employees to Take
Responsibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii65
Checklist for Audiometric Evaluations. . . ii65
8 Making Sure That the HCP Works. . . . . . . . . ii67
The Team Approach . . . . . . . . . . . . . . . . . . . . . . . ii67
Documentation and Recordkeeping . . . . . ii67
Recording Hearing Loss on the OSHA
200 Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii68
Assessing Your HCP. . . . . . . . . . . . . . . . . . . . . . . ii70
Audiometric Data Base Analysis
( ADBA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii71
Checklist for HCP Evaluation . . . . . . . . . . . ii76
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii77
Resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii80
v
Foreword
The ear is a delicate organ. Serious damage to the
ears can leave a person partially or completely deaf.
Sudden extreme loud noise or prolonged loud noise may
cause permanent injury to the hearing. Workers in very
noisy industries may be affected over time if hearing
protection programs are not initiated and followed.
Employers must be aware of workplace hazards facing
their employees and take appropriate action to minimize
or eliminate exposure to these hazards. A Guide to
Developing and Maintaining an Effective Hearing
Conservation Program describes a program that
employers can implement to protect their employees’
hearing ability.
In this state, the North Carolina Department of Labor
consultants and inspectors administer the federal OSHA
laws through a plan approved by the U. S. Department of
Labor. All current OSHA standards are enforced. Many
educational programs, publications ( including this
guide), and other services are also offered to help inform
people about their rights and responsibilities regarding
OSHA.
As you look through this guide, please remember that
OSHA’s mission is greater than just enforcement. An
equally important goal is to help citizens find ways to
create safe and healthy workplaces. Reading and using
the information in this booklet, like other educational
materials produced by the North Carolina Department
of Labor, can help.
Cherie K. Berry
Commissioner of Labor
vi
Introduction
This publication describes a program that employers
can implement to protect their employees’ hearing abili-ty.
The writers intended to take the reader beyond the
minimum provisions of OSHA requirements. They did
not intend to create a guide to the OSHA occupational
noise exposure standard. If at any point the OSHA stan-dard
and information here should appear to conflict, the
standard must be considered controlling. Therefore, the
reader should be acquainted with the OSHA standard.
The occupational noise exposure standard is included
in the North Carolina OSHA Standards for General
Industry. Contact the Standards, Analysis, and
Publications Section, Division of Occupational Safety
and Health, North Carolina Department of Labor, for a
copy of the standards and for assistance in interpreting
them. ( See the inside back cover of this publication for
the address and telephone number.)
The occupational noise exposure standard is at 29
CFR 1910.95. Parts of the standard that provide particu-larly
helpful background for reading this guide include:
Sections .95( c)–( oo)— inform of the circumstances
under which the employer must implement a hearing
conservation program ( HCP) and describe the elements
of an acceptable HCP
Section .95( b)( l)— requires the use of feasible adminis-trative
and engineering controls
Section .95( f)— provides that employees must be pro-vided
an opportunity to observe noise measurements as
they are conducted
Section .95( l)— describes types of information ( includ-ing
copies of the standard) that must be posted in the
workplace and/ or otherwise made available to employees
vii
Section .95( i)— requires employers that are required
to establish an HCP:
• provide hearing protectors at no cost to employees
• allow employees to select from a variety of hearing
protectors
• ensure the proper initial fit of hearing protectors
• train employees in the use and care of the hearing
protectors that they select for their use
• ensure that employees wear their hearing protec-tors
viii
1
Effective Hearing
Conservation Programs ( HCPs):
Benefits and Strategies
The purpose of industrial hearing conservation pro-grams
( HCPS) is to prevent employees from developing
noise- induced hearing loss on the job. After occupational
hearing loss was recognized as a health problem, the
Occupational Safety and Health Administration ( OSHA)
promulgated regulations that specified minimum
requirements for employers to meet. However, simply
complying with the OSHA regulations does not guaran-tee
that a program will be effective in preventing occu-pational
hearing loss, as many unsuccessful HCPs
demonstrate.
If the employer runs an ineffective HCP, there is no
payback for the time and resources invested. An ineffec-tive
HCP is only an exercise in regulatory compliance.
However, the goal of preventing occupational hearing
loss can be achieved if the employer applies a few basic
principles in organizing the HCP. Our experience with
industries across the country indicates that there is no
correlation between the amount of money spent on the
HCP and its effectiveness. However, if management
ensures that the HCP has the desired characteristics
described in this guide, the program will succeed.
A Look at HCPs Nationwide
During 1980– 84 the authors of this publication
received a grant through N. C. State University from the
E- A- R Division of Cabot Corporation to conduct on- site
interviews with HCP personnel nationwide to describe
1
the use of hearing protection devices ( HPDs) in 218
industries of all types. In addition to the structured
questionnaire results about HPDs, comments from
those interviewed and observations provided insights
about common mistakes in HCP implementation and
organization. Some frequent causes of HCP ineffective-ness
are shown in table 1.
Table 1
Frequent Causes of HCP Ineffectiveness
By avoiding pitfalls such as those shown in table 1
and by following the tips in this booklet, the employer
can develop an effective HCP. The policies and proce-dures
outlined in this publication have proved useful in
HCPs in a variety of industries around the United
States and will probably apply to most production facili-ties.
Nevertheless, because it is impossible to specify
2
• Inadequate communication and coordination among: ( 1) plant
personnel involved in the HCP and ( 2) on- site personnel and
corporate headquarters
• Insufficient or erroneous information used to make HCP
decisions
• No meaningful training for HPD fitters and reissuers
• Inadequate or inappropriate selection of HPDs in stock and
over- reliance on noise reduction ratings in choosing HPDs
• Failure to fit and train each HPD wearer individually
• Over- reliance on contractors to provide HCP services
• Failure to use the audiometric monitoring results to educate
and motivate employees
• Failure to use audiometric data to evaluate the effectiveness
of the HCP
HCP guidelines to cover every situation, the hearing
conservationist has to use common sense in evaluating
whether particular pieces of advice are workable for
each plant’s HCP. Local personnel can judge best how to
tailor the guidelines for their facility in order to achieve
the goal: prevention of occupational hearing loss.
Benefits of the HCP to the Employee
Preventing hearing loss on the job is the primary
employee benefit of the HCP, but just why is this impor-tant?
Hearing loss from any cause reduces the quality
of life for the affected individual. Hearing impairment
interferes with normal communication, and communica-tion
is a significant part of life. For many jobs we need
adequate hearing to qualify to be hired or promoted, so
hearing loss decreases our employment potential. On
the job we need good communication ability to give and
receive instructions, use the telephone, and detect
machinery sounds and warning signals. Off the job our
interpersonal communication with family and friends
puts pleasure in our lives and gives us a feeling of being
involved with others in recreational situations and at
home. We also need our hearing to enjoy music and the
quiet sounds of nature. For all of those reasons and
more, good hearing is invaluable.
The HCP also provides a health screening benefit for
employees, since nonoccupational hearing losses and
potentially treatable ear diseases are often detected
through the annual audiograms.
Benefits of the HCP to the Employer
The employer benefits directly by implementing an
effective HCP that maintains employees’ good hearing,
since workers will remain more productive if their com-munication
abilities are not impaired. Employees with
good hearing are also more versatile and can be promoted
3
to jobs where communication ( especially by telephone) is
even more important. Effective HCPs can reduce accident
rates and promote work efficiency, as well as reduce the
stress and fatigue related to noise exposure.
The HCP is one aspect of the employer’s overall poli-cy
toward worker health and safety practices, and
employee relations are better and job turnover is lower
for companies that pay attention to the working envi-ronment.
Maintaining a safe and healthy workplace
contributes to the company’s prestige and image as a
desirable employer.
An effective HCP also lessens monetary losses from
workers’ compensation claims and insurance premiums.
Further, the effective HCP is cost- effective in that while
compliance with OSHA and other governmental regula-tions
is achieved, loss prevention and productivity gains
are also realized.
4
2
Organizing Your HCP:
Five Phases under a Key
Individual
Figure 1 presents an outline of the major aspects of a
HCP. The five phases of the program are shown in the
first column. The second column lists characteristics
that differentiate effective HCPs from unsuccessful pro-grams.
The third column indicates various company per-sonnel
who are important to HCP success. The fourth
column lists influences external to the company that
may also affect the HCP. Each of these aspects is dis-cussed
below, and additional information is available.
( See References, items 1 and 2.)
Five Related Phases
The phases of every HCP are education, sound expo-sure
surveys, engineering and/ or administrative noise
controls, hearing protection, and audiometric evalua-tions.
The relative emphasis placed on the phases may
vary according to the needs of the particular production
facility, but each one is essential for an effective program.
The Education Phase
The education phase is the most important because
HCP personnel and employees will not actively partici-pate
in hearing conservation unless they understand its
purpose and how they will benefit directly from the pro-gram,
and know that compliance with the company’s
safety and health requirements is a condition of employ-ment.
Without meaningful education to motivate indi-vidual
actions, the HCP will fail. Educational efforts
must begin even before sound surveys and engineering
5
6
Hearing Conservation Program
Five
Phases
Desired
Characteristics
Personnel
Involved
External
Influences
Company
Headquarters
Top
Management
Enforcement of
Hearing Protec-tion
Utilization
Engineering
Administrative
Controls
Middle
Management
Key
Hearing Individual
Protection
Audiometric
Monitoring
Active
Communications
Education Top Manager
Sound Surveys
Consultants
Suppliers
Second Job
Community
Supervisors
Employees
Leisure Time
Hobbies, etc.
Potentially
Effective
Hearing Pro-tection
Devices
Figure 1
Hearing Conservation Program ( HCP) Phases,
Desired Characteristics, Personnel Involved, and
External Influences That Affect HCP Function
controls are carried out in order to obtain representative
exposure results and to develop employee acceptance of
machine modifications. Likewise, the success of the
hearing protection and audiometric phases depends on
teaching employees how to understand and take care of
their hearing. In effective HCPs the educational phase is
continuous— not just an annual presentation— as HCP
personnel take daily opportunities to remind others
about conserving their hearing.
The Sound Survey Phase
The sound survey phase involves determining the
degree of hazardous noise exposure for workers so that
appropriate HCP policies can be established to protect
them. For example, the choices of hearing protectors
available to employees may be limited to the most
effective devices for departments with very high noise
exposures. In addition, sound surveys can identify the
dominant noise sources in each area of the plant and
determine where engineering controls can significantly
reduce employee exposures.
The Engineering and Administrative
Noise Controls Phase
The engineering and administrative noise controls
phase attempts to reduce employees’ noise exposures to
nonhazardous levels. Engineering controls involve modi-fication
of the noise source ( such as by fitting mufflers to
air exhaust nozzles), the noise path ( such as by placing
sound- absorbent enclosures around equipment), or the
receiver ( such as by constructing an enclosure around
the employee’s work station). Administrative noise con-trols
include changes in employees’ work schedules or
task assignments to reduce noise exposures by limiting
exposure time. The ultimate goal is to eliminate employ-ee
exposures to harmful noise. However, significant
reductions in exposure are very important because it is
much easier to achieve effective protection for employees
7
using hearing protection devices if the exposures are
lower rather than higher. Application of retrofit noise
controls to existing machinery may be effective. But
when the employer purchases new equipment, an excel-lent
opportunity exists to demand reduced sound level
output as part of the specifications required of the equip-ment
manufacturer. In addition, regular maintenance
programs for equipment and for its noise control modifi-cations
help keep noise levels down as well as extend the
life of the machinery.
The Hearing Protection Phase
The hearing protection phase of the HCP provides
hearing protection devices ( HPDs) for employees and
training in how to wear them as long as hazardous
noise levels exist in the workplace. Because feasible
engineering noise controls have not been developed for
many types of industrial equipment, HPDs are the best
current option for preventing noise- induced hearing loss
in these situations.
The Audiometric Evaluations Phase
The audiometric evaluations phase of the HCP ties
together the whole program. Each exposed employee
receives an annual hearing cheek to monitor hearing
status and detect any hearing change. If the HCP is
working, employees’ audiometric results will not show
changes associated with on- the- job noise- induced hear-ing
damage. If suspicious hearing changes are found,
the audiometric technician and the audiologist who
reviews the record can counsel the employee to wear
HPDs more carefully, assess whether more effective
HPDs are needed, and motivate the individual to be
more careful in protecting his or her hearing both on
and off the job. Sometimes nonoccupational causes of
hearing change may be identified, such as gunfire or
hobby noise exposure or medical ear problems.
8
Characteristics of Effective HCPs
HPDs— Effective and Enforced
The importance of HPD policies to HCP success is
underscored by the first two desired characteristics of
effective HCPS: strict enforcement of HPD utilization
( actual enforcement, not just a paper policy) and the
availability of HPDs that are potentially effective for the
work environment. Potentially effective HPDs are
devices that are practical and comfortable enough for
employees to wear them consistently and provide ade-quate
sound attenuation.
The Key Individual
The most important strategy for making the five
phases of the HCP function together effectively is to
unite them under the supervision of one key individual.
In smaller companies where one person may actually
carry out all facets of the HCP, lack of coordination is
not usually a problem. However, as company size
increases, different types of staff become involved in the
HCP: safety personnel, medical personnel, engineers,
industrial hygienists, tool crib supervisors, and produc-tion
supervisors. With personnel from varying disci-plines
carrying out different aspects of the program, it
becomes very difficult to coordinate their efforts unless
one key individual is overseeing the entire HCP. The
choice of who this person should be is critical to the suc-cess
of the program. The primary qualification for the
key individual is genuine interest in the company’s HCP.
Nonetheless, selecting the key individual does not mini-mize
the crucial importance of the line supervisor to the
success of the HCP.
Since extra training is easy to obtain through brief
courses such as those approved by the Council for
Accreditation in Occupational Hearing Conservation
( CAOHC) ( see Resources, item 2), the background of
the key individual is less important than his or her
9
enthusiasm and ability to relate to people. The key
individuals we have observed know everyone by name
and are equally friendly with production employees
and managers. The key individual is approachable and
is always sincerely interested in comments or com-plaints
that can help to improve the HCP. This individ-ual
does not stay in an office, running the HCP on
paper by mandate, but spends time on the production
floors to interact with employees and observe how prob-lems
can be prevented or solved.
Active Communications
The key individual maintains communication among
all company personnel involved in the HCP by passing
information both up and down the hierarchy. The pri-mary
HCP team members meet together regularly to
update each other on the progress of the program. Once
people with different tasks understand how their own
parts contribute to the overall outcome of the program,
they will respond to feedback about their performance
by cooperating to prevent hearing loss. The key individ-ual
can achieve this active communication and coopera-tion
if management provides him or her with the
authority to make HCP decisions and the resource
allocations to act on decisions once they are made.
Personnel Involved in the HCP
The success of the HCP depends on everyone from the
top manager to the most recently hired trainee; each has
an important role. For management, the role is largely to
support the HCP and enforce its policies as one facet of
the company’s overall health and safety program. For
middle management and supervisors, the role is more
direct: these staff members are part of the primary HCP
team, which carries out the five phases. Their duties
include monitoring noise exposures, maintaining engi-neering
controls, participating in educational efforts, fit-ting
HPDs and reissuing HPD replacements, supervising
10
daily HPD utilization, performing the audiometric evalu-ations,
and giving feedback to employees about their
hearing results. The role of employees is to participate
actively in the program and to make suggestions as to
how to improve HCP operation. However, for employee
participation to succeed, the HCP team must be receptive
to comments and respond to employee input.
External Influences on the HCP
If local HCP decisions are limited by policies mandat-ed
by corporate headquarters, the key individual may
need top management’s assistance in obtaining excep-tions
to the corporate rules in order to meet local needs.
The key individual also must keep control over any ser-vices
provided by outside contractors ( such as sound
surveys or audiograms). When contractors are used, it
is more difficult to integrate their services cohesively
into the overall HCP, but it is critical to do so. If in-plant
personnel do not follow through by using the
information provided by the contractors, then the con-tracted
elements of the program lose effectiveness.
Finally, employees’ hearing is affected by off- the- job
activities such as recreational target shooting or use of
power tools in farming or woodworking. The HCP can-not
save workers’ hearing through protection on the job
unless employees are educated to protect their ears dur-ing
off- the- job noise exposures. The wise employer
encourages employees to take HPDs home for use in
nonoccupational noisy situations. Meaningful educa-tional
programs focus on the importance of good hear-ing
for enjoyment of social and recreational activities, so
the employee will appreciate the employer’s concern for
hearing conservation in all parts of life.
11
Organization Makes the Difference
Most HCPs make at least some efforts in each of the
five phases, but most programs remain ineffective
because they are fragmented and incomplete. When
HCP personnel lack adequate training to carry out their
duties, have no direct supervision to coordinate their
efforts, and are not evaluated on their performance, the
HCP fails. By putting an interested and capable person
in charge of all five phases, then authorizing this key
individual to make decisions and take actions to
improve the program, management will be rewarded by
a cost- effective, successful HCP.
Checklist for HCP Development
All five HCP phases have been implemented.
There is a key individual in charge of the HCP
team.
HPDs are potentially effective in actual use.
HPD utilization is enforced.
There is active communication among the HCP
team members and personnel at all levels.
12
3
Education and Motivation
Education and motivation are critical to helping
employees actively participate in the HCP and generat-ing
the sincere support of the program by management.
Regular educational and motivational activities related
to hearing conservation develop interest in the program
and keep the importance of the HCP in mind through-out
the year. Any HCP that attempts to skip over this
phase of the program will find other phases failing
because personnel do not understand why it is in their
own best interest to cooperate in the HCP and take
advantage of its benefits. For more details about educa-tion
and motivation, see References, items 3 and 4.
Education Paves the Way for Other
Phases
When sound surveys are planned to determine
whether a HCP needs to be established, limited educa-tional
efforts must come first to notify supervisors and
employees about the purpose of the sound surveys and
to explain that their assistance is important for obtain-ing
accurate sound measurements. Employees will be
much more cooperative if they are informed in advance
of what will be happening and why.
If a noise problem is identified during sound surveys,
then a more formal educational program needs to be
given before the noise control, hearing protection, and
audiometric evaluation phases of the HCP are initiated.
This start- up program would present the results of the
sound surveys, explain the risks of noise- induced hear-ing
loss, and introduce the HCP policies established for
various areas or departments of the plant.
13
Making Education a Priority
Management must emphasize the importance of the
educational phase by scheduling regular training ses-sions
and requiring attendance. Educational sessions
should be held not only for employees who are regularly
over- exposed to noise, but also for employees who occa-sionally
enter the HPD- required areas of the plant and
for the supervisors and managers responsible for pro-duction
areas with hazardous noise. When a company’s
HCP is being introduced, a manager should participate
in each educational session to outline company policies
and demonstrate the company’s commitment to the
HCP. In an established HCP, a manager should partici-pate
in educational sessions to the degree practical to
reinforce the company’s priority on the HCP.
Developing Adequate Personnel
Resources
Management must ensure that the primary HCP team
members ( the key individual, audiometric technicians,
HPD fitters and issuers, and supervisors) have received
sufficient education about hearing conservation. Then
they will be qualified and comfortable carrying out their
HCP responsibilities, as well as leading employee train-ing
sessions and answering employees’ questions. The
success of the program depends on this team.
Organizing Sessions for Best Results
The educational sessions work best in small groups con-sisting
of the presenters plus the supervisor and employees
in a production unit. These individuals will typically have
common noise exposures, will fall under a common HPD
policy, and will feel comfortable enough with each other to
ask questions freely. Management must also ensure that
employee questions and concerns raised during educational
sessions receive thoughtful and prompt follow- up. Separate
14
sessions should be held for supervisors of noisy depart-ments
and their managers, so that they can discuss com-pany
policy concerns prior to meeting with employees.
These groups need more detailed information to prepare
for questions employees may later ask during educational
sessions or when back in their departments.
A Relevant Approach to Education
To hold employees’ interest, the personnel who make
the main presentations in formal educational programs
must be selected to project genuine interest in employees’
welfare, and the program content must be updated every
year.
Keep it:
• Short
• Simple
• Meaningful
• Motivating
The annual educational program covers practical aspects of all five
phases of the company‘ s HCP and gives employees a chance to ask
questions.
15
Educators should limit the content to a brief, simple
presentation of the most relevant facts for employees.
The focus should be on the real- life reasons of why it is
to the advantage of employees to protect their hearing
in order to maintain their quality of life: to preserve
speech understanding ability in both work settings and
social environments, to enjoy music, and to perceive
auditory warnings and signals such as car engine noises
that indicate malfunctions.
Information to help employees understand how their
audiogram results compare to expected age- effect hear-ing
loss will increase the motivational benefit of the
audiometric phase. Once employees are familiar with
their audiogram results and know the reasons why they
need to preserve their hearing, the remainder of the
program can focus on how to protect their hearing on
and off the job. Employees protect themselves by the
effective use of HPDs and engineering noise controls,
plus administrative controls including good general
maintenance of production equipment. The educational
program should stress how the HCP benefits employees
by protecting their hearing at work and detecting hear-ing
changes that result from medical conditions and
nonoccupational noise exposures. A sample educational
outline is shown as table 2.
16
17
Table 2
Suggested Educational Program Content
How noise damages our hearing
Consequences of hearing loss in everyday life
Diminished ability to understand speech
Social isolation from friends and family
Interference with work and leisure activities
Noise exposures that are hazardous
Off the job ( gunfire; power tools)
On the job ( sound survey results for plant)
Engineering and/ or administrative noise controls imple-mented
or planned
HPD choices for the employees’ department
Using them correctly
Caring for and replacing them
Solving common HPD problems or complaints
Audiometric evaluations— purpose and procedures
Understand your own audiogram results
Hearing changes may mean inadequate protection
Nonoccupational hearing loss may be detected
Ways to protect your hearing on and off the job
Wear HPDs correctly and consistently
Avoid unnecessary noise exposures
Use engineering and administrative noise controls
The company’s HCP policies
The importance of the HCP to management
HCP participation as a condition of employment
Questions and answers
Final motivation
The HCP as a benefit for employees
Participation is to employees’ own advantage
Tailoring the Presentation to the
Audience
Presenters need to make the educational program’s
content specific to the particular group of employees
attending with their supervisor. Presenters should
mention the employees’ specific noise exposures, the HPD
options available, and the engineering controls in place or
planned for their department. For the separate sessions
for supervisors and managers, greater details and differ-ent
emphases are appropriate to address the concerns of
these personnel. Such sessions may present a progress
report on the status of the HCP, review of the company’s
legal obligations for regulatory compliance, comparisons
of audiometric and HPD utilization indicators by depart-ment,
and answers for questions that employees may ask.
Films and pamphlets should be used only as supplemen-tary
reinforcements for live presentations, never as the
whole program. Verbal presentations and audiovisual
aids should be changed annually.
People with noise- induced hearing loss usually find it hard to understand
the high- pitched voices of children and women. By protecting your hear-ing,
you can prevent noise damage from affecting your family life.
18
Taking Advantage of Motivational
Opportunities
Aside from formal educational presentations, HCP
personnel should use every chance to remind employees
and supervisors of the importance of the HCP and their
active participation in it, especially concerning hearing
protection. The greatest opportunity to influence
employees occurs at audiogram time, when the current
hearing results can be compared to past results and the
fit and condition of HPDs can be checked. Praise for
employees with stable hearing and cautions for those
with threshold shifts can be effective if the comments
come from a sincere individual. The personnel who real-ly
make HCPs come alive do not wait for this once- a-year
chance to interact with employees. They tour the
plant floor making comments and talking to workers in
the halls and cafeteria. HCP personnel need to empha-size
hearing conservation as an ongoing effort. This can
be achieved through safety meetings, rewards for
departments with excellent HCP performance, bulletin
board posters, articles in the company paper, and daily
interactions with employees. The goal is to emphasize
the HCP continually as part of the company climate.
Questions and Suggestions
Employees need time during educational sessions,
safety meetings, and their daily work to voice their con-cerns
or questions. They need the opportunity to inform
HCP personnel when certain HPDs or engineering con-trols
are not practical and to suggest alternatives that
would be more workable for their departments. If HCP
personnel do not provide adequate follow- up or consid-eration,
employees need to be able and encouraged to go
up the management line until their concerns are
addressed.
19
Checklist for Education and Motivation
Team members receive education about hearing
loss and hearing conservation to understand the
goals and policies of the HCP.
HCP team members receive training in how to
carry out their functions ( especially concerning
HPD fitting and utilization).
Employees annually attend updated educational
programs that focus on why and how to protect
their own hearing on and off the job.
HCP personnel keep the program in employees’
minds through informal reminders at least quar-terly.
Management backs up the HCP by personal exam-ple
( wearing HPDs), policy enforcement, and par-ticipation
in educational programs.
Employees are evaluated on their HCP participa-tion
during the company’s annual personnel
reviews.
20
4
Sound Surveys
The noise measurement data obtained through sound
surveys is needed to determine the degree of exposure
hazard and to make decisions about how to protect
employees. Different instruments and measurement
methods may be used depending on the type of survey
being conducted.
Types of Surveys and Instrumentation
In basic sound surveys a sound level meter is used to
identify work areas that clearly do not have a noise
problem and areas that do have potentially hazardous
noise environments. The basic survey determines the
departments where employees may need to be included
in the HCP due to their daily noise exposures ( a combi-nation
of the noise levels with their corresponding dura-tions).
In detailed sound surveys, a sound level meter
and stopwatch and/ or a personal noise dosimeter are
used to estimate the worker’s daily noise dose and
equivalent OSHA time- weighted average ( TWA) noise
exposure. In engineering sound surveys instruments
such as sound level meters, octave- band analyzers, and
recorders may be used to measure the noise levels pro-duced
by machinery in various modes of operation in
order to assess the potential for applying engineering
controls.
Surveys should be conducted on a recurrent basis:
annually, or more often if it is suspected that the
employees’ TWAs may have changed significantly. Thus,
it is often cost- effective to purchase the instrumentation
and have an on- site staff member trained to perform
sound level and exposure measurements. With in- house
expertise, the company can check sound levels whenever
21
production machinery is changed without bringing in an
external consultant. In addition, company personnel can
evaluate simple noise control options without having to
hire a consultant.
Ways Sound Survey Results Are Used
The results of sound surveys are needed for many
reasons:
• To designate those areas of the plant where haz-ardous
noise levels exist
• To identify the employees to be included in the
HCP
• To classify employee noise exposures in order to
define HPD policies and rank areas for noise con-trol
efforts
• To determine whether noise levels present a safety
hazard in terms of interference with speech com-munication
and warning signal detection
• To evaluate noise sources for noise control purposes
• To document noise levels and employee exposures
for legal purposes such as workers’ compensation
Keeping Surveys in Perspective
It is important to define the goals of the sound surveys
and limit their scope to obtaining the information needed to
guide decisions. It is not necessary to perform extremely
detailed surveys to decide how best to protect employees. In
many instances adequate data can be obtained with only a
sound level meter and a stopwatch. The time and money
devoted to exposure monitoring should be just sufficient to
make appropriate HCP decisions. The bulk of resource allo-cations
should go to the phases of the program that actually
provide protection for employees ( education, noise controls,
hearing protection, and audiometric evaluations).
22
The sound survey should result in a noise map of the
production facility. A noise map is a floor plan with
areas of the plant designated according to whether area
workers are included in the HCP and according to
which HPD utilization policy applies to the area: volun-tary
or required use, with free or restricted HPD choice.
( See table 3). Estimates of daily noise exposures for rep-resentative
employees in various jobs are also needed,
particularly for jobs in which workers are exposed to
noise that varies in level. A suggested guideline for clas-sifying
HCP policies according to the established TWAs
is shown in table 3.
Table 3
Suggested TWA Ranges for Classifying Plant Areas and
Corresponding HCP Policies for Area Employees
Planning and Coordinating with
Production Personnel
HCP personnel must plan the sound surveys to
obtain information needed to answer relevant questions
about protecting employees. If external contractors per-form
the surveys, the key individual must define the
information desired and familiarize the contractors
23
TWA, dB( A) Workers in HPD HPD Selection
the HCP Utilization Options
84 or below no voluntary free choice
85– 89 yes optional* free choice
90– 94 yes required free choice
95– 99 yes required limited choice
100 or above yes required very limited
choice
* HPD utilization will be required:
1. For any individual who shows a significant change in hearing
2. For all employees if audiometric data base analysis results
or group hearing trends indicate inadequate protection
with the environment, employee work schedules, and
production variations. Following this procedure ensures
that the desired information will be obtained.
The sound surveyor must coordinate scheduling with
production personnel to capture representative produc-tion
cycles. Supervisors can predict when noise levels will
be higher or lower, when certain pieces of equipment will
be in operation, and when downtime for repairs or main-tenance
will be scheduled. Production schedules and
machinery function do not always follow predictions.
Thus, surveyors must be flexible and return as needed to
obtain the desired data for all typical work activities. By
coordinating with supervisors to minimize interference
with production, the surveyors will enhance supervisors’
cooperation and willingness to share information.
Employee cooperation and knowledge are needed to
obtain valid survey results. Therefore, sound surveyors
must establish rapport with workers to benefit from
their familiarity with the production environment and
machinery. Experienced operators can often identify
dominant sound sources, predict time periods of relative-ly
higher or lower sound levels, and describe the effects
of different operation modes on sound levels. If survey-ors
explain the purpose of the survey to workers and
solicit their help in planning the measurements to be
made, they can avoid errors and oversights and reduce
the prospect of resentful or suspicious workers sabotag-ing
the results or damaging the instrumentation.
Data Collection
In making measurements and documenting results,
the surveyors must consistently follow accepted prac-tices
for instrument selection and calibration, measure-ment
techniques, sampling strategy, methodology
description and documentation, and data recording.
Detailed guidelines for data collection are available. ( See
References, item 5.) The American National Standards
24
Institute ( ANSI) also publishes relevant standards. ( See
Resources, item 1.) During data collection, the surveyor
must record in detail the measurement locations and
times and the procedures followed. A good rule of thumb
is to make the survey description detailed enough that
another person could follow it to replicate the results
( provided the noise environment has not changed). It is
very useful to record C- weighted as well as A- weighted
sound levels for purposes of estimating HPD adequacy
and considering engineering controls. ( For more infor-mation
about C- weighted and A- weighted sound levels,
see References, item 12.)
A noise dosimeter takes into account the variations in sound levels over
time and predicts the employee’s daily noise dose, which can be con-verted
to the TWA.
Employee Participation Is Essential
Employees can assist the sound surveyors in obtain-ing
representative results by sharing their knowledge
about the production environment, the machinery in
operation, and worker tasks. Employee assistance is
critical in operating machinery for detailed engineering
25
sound surveys intended to evaluate sound sources with-in
a unit of machinery. Employees should continue their
normal activities when wearing dosimeters for individ-ual
worker exposure monitoring to ensure that the
results will be representative.
Employees should be asked to notify HCP personnel
when the sound environment creates a possible safety
hazard due to communication difficulty or when
changes in sound levels call for a resurvey. Sound levels
may increase significantly when equipment begins to
wear, and changes in equipment placement or processes
may have unintended effects on sound levels. When
employees notice such changes, they need to inform the
sound surveyors that a resurvey is needed to evaluate
the sound levels and corresponding employee exposures.
Report Preparation
The report written after completing the sound survey
must present the results clearly. The writer should
state the survey objectives and present data relevant to
these objectives. Because few report users will need or
read the full details of the survey, it is critical to include
a concise abstract or administrative review section. A
slightly longer summary should be included for the pri-mary
HCP team.
The body of the report must summarize the calibra-tion
and measurement procedures to support the validi-ty
of the conclusions. Detailed documentation must be
kept with the report to substantiate the procedures if
they are ever questioned. Although the report will con-tain
neatly organized tables of data, the original data
recording sheets and instrument calibration sheets
should be preserved for potential legal purposes. Keep
in mind that all sound survey reports may be used as
legal documents if the company ever becomes involved
in a workers’ compensation or other suit related to the
noise environment.
26
Communicating Exposure Results
The written abstract of sound survey results should
be given to managers and department supervisors, and
the longer summary should be given to the HCP team
members. The updated noise map of the plant should be
explained to employees during their educational pro-grams
and posted for employees to refer to. In areas
where hearing protectors are required for all who enter,
warning signs should be posted. Employee TWA esti-mates
must be transcribed onto the audiometric records
for individual employees to aid the audiogram reviewer
in interpreting whether hearing trends are caused by
on- the- job noise exposure.
Checklist for Sound Surveys
Representative TWAs have been determined for
all noise- exposed job classifications.
A noise map of the plant has been posted to show:
1. areas where employees are included in the HCP
2. areas where HPD utilization is required.
Employees have been told the typical noise expo-sures
for their departments during educational
sessions.
HCP team members and department supervisors
have summaries of sound survey results.
Employee TWAs are listed on their individual
audiometric records.
27
5
Engineering and
Administrative Noise Controls
Engineering Controls
If real- world noise sources such as production equip-ment,
fans, and air compressors that overexpose
employees can be quieted so that their contribution to
the employees’ daily TWA is no longer important, and if
the cost of controlling the sources is less than the cost of
not controlling them, then the noise problems should be
controlled. However, real- world situations are seldom
clear- cut. Making management and engineering deci-sions
concerning the anticipated effectiveness and cost
of noise control options is often a challenge to all parties
involved ( managers, equipment manufacturers, OSHA
personnel, and consultants).
For example, consider a situation where a long- term
financial benefit would result ( increased production and
lower cost per unit produced) if known noise control
solutions for a piece of production equipment were
installed. It is also known that installing noise controls
would lower the employees’ TWA by at least 5 dB( A).
However, the capital to carry out the modifications is
not available. Therefore, in this situation the monetary
constraints would delay known noise control options in
favor of the utilization of hearing protection until the
company is financially able to make the necessary
equipment modifications. Management should recognize
that failure to make the changes as soon as practical
would reduce the company’s ability to compete in the
free market.
28
What is management’s responsibility with respect to
the engineering and/ or administrative noise control
phase of the HCP? For any plant site, management has
the responsibility to identify the dominant noise sources
in all production areas and determine if practical noise
control options are available and if the cost of noise con-trols
is justified. It is not adequate for management to
say, prior to conducting the engineering noise control
survey, that production equipment A is the noise prob-lem
and no solution exists. It might be that uncon-trolled
air exhaust or an improperly installed hydraulic
valve, both problems that are often easily controlled,
are the only major noise sources creating the overexpo-sure
for the operators of the equipment. Whereas iden-tifying
the dominant noise sources in a production area
is typically easy to do, determining the reasonableness
of the anticipated cost is more difficult.
Identifying Dominant Noise Sources
During the basic or detailed sound survey, the sur-veyor
should have identified the obvious dominant noise
sources in the room. This information is now used as
the starting point for the engineering noise survey,
which will determine the contribution of each dominant
source to employee noise exposures.
Using a sound level meter, the surveyor can measure
the sound levels at the employee’s workstation as individ-ual
pieces of equipment in the production area are run
separately, to determine their relative contributions. In
some circumstances it is not practical to run individual
pieces of equipment ( due to continuous equipment opera-tion
and/ or equipment interdependence). Then it will be
necessary to conduct the survey during the yearly main-tenance
period or to make measurements at times when,
due to equipment failure or temporary equipment shut-downs,
one or more of the production units is not operat-ing.
Once the noise levels at the employees’ work stations
are known with different units in operation, then the
29
effective contribution of each piece of equipment can be
easily determined. For more information, see References,
item 5.
Contributing Equipment Noise Sources
Once the dominant noise sources have been defined,
the next step is to determine the significant contribut-ing
noise sources within each piece of equipment.
Typically this survey involves a team consisting of
equipment operators, a mechanic, and a sound survey-or.
As far as the machinery design will allow, individual
components of the equipment are operated and the
noise levels at the employee’s workstation are recorded
for each operating condition. The ideal situation occurs
when one component of the equipment is found to be
the only significant sound source and a readily avail-able,
inexpensive noise control solution exists.
One Example
In a production room the measured TWA of stamping
machine operators was 93 dB( A), and TWAs of 88 dB( A)
were measured for employees in another area of the
room who were packing the product. ( Note that the
level of the noise in the room was constant and roughly
equal to the predicted OSHA TWA.) For employees
working in both areas, noise exposures were below 80
dB( A) when the stamping machines were not running
but the heating, ventilating and air conditioning
( HVAC) system was in operation. Therefore, it was con-cluded
that the dominant noise sources in this produc-tion
room were the stamping machines.
The next step was to operate one stamping machine
while the remaining machines were not running. Due to
production constraints, this required the sound testing
to be carried out between second and first shifts. The
survey team consisted of the company’s chief mechanic
and the sound surveyor.
30
The stamping machine could be run without any
product being stamped, and the air supply used to
assist in the removal of the product could also be turned
off. Therefore the test sequence followed involved run-ning
the stamping unit with the air supply turned off
and without product ( condition 1), then with the air
supply on but without product ( condition 2), and finally
turning out product with the air on ( condition 3). For
condition 1 the measured sound level at the employee’s
work station was less than 80 dB( A). When the air was
turned on ( condition 2), the sound level increased to 90
dB( A). Finally, for condition 3 the sound level increased
by 0.5 dB( A) to 90.5 dB( A). Note that if the addition of
the product ( condition 3) had contributed as much to
the measured noise level as did the air supply ( condi-tion
2), then the increase in level for condition 3 would
have been 3 dB( A). Because the increase was only 0.5
dB( A), it was concluded that the contribution from run-ning
product was at least 10 dB less than the contribu-tion
of the basic machine components plus the air noise.
After identifying the air exhaust system of the stamp-ing
machines as the room’s major contributing noise
source, management had the information to determine
the feasibility of controlling the noise to reduce employ-ees’
exposures. Since the measured sound level at the
operator’s work station was 90.5 dB( A) with only one
stamping machine running, and the workstation level
increased to 93 dB( A) with all units in operation, then
the increase of 2.5 dB( A) was due to the contribution of
the remaining stamping machines. In other words,
noise controls needed to be applied not only to the oper-ator’s
own machine, but also to all other surrounding
units, to reduce the noise level at the employee’s work
station to below 85 dB( A).
31
Many common noise problems, such as air exhaust noise, are simple to
control with commercially available mufflers.
In this case a solution was both economically and
technically feasible. For expenditure of less than $ 15.00
per stamping machine, management was able to com-pletely
eliminate the noise hazard to below OSHA
requirements. Without the engineering noise control
survey, however, management would not have had the
information necessary to make the appropriate decision.
Feasibility Considerations
When conducting the engineering noise control surveys,
several pieces of production equipment are commonly
found to be dominant noise sources, contributing about
equally to the employee’s daily TWA. Each of these domi-nant
noise sources may have included several equally con-tributing
component noise sources. Even when feasible
solutions are known for some of the contributing sources,
the existence of multiple sources may make it possible to
conclude that controlling the employee’s noise exposure
32
cannot be economically justified. However, the pieces of
production equipment that are the dominant sound
sources and their internal contributing noise sources must
first be identified. Otherwise, management will not have
the necessary technical information to accompany other
information ( such as effects on production and cost) upon
which to base appropriate decisions concerning controlling
the noise through engineering means.
Administrative Controls
The most common interpretation of the term “ admin-istrative
controls” includes the use of changes in
employees’ work schedules and job tasks to reduce the
noise exposures for individuals. Many people consider
the purchase of quieter new equipment to be an engi-neering
noise control. However, such “ buy quiet” efforts
are more of a managerial decision than an engineering
effort, since the purchaser transfers the responsibility
for engineering out the noise to the equipment manu-facturer.
To distinguish the application of retrofit noise
controls in the local plant from “ buy quiet” programs,
the purchase of quieter new equipment is interpreted
here as an administrative noise control. Also considered
here to be an administrative noise control is manage-ment’s
establishment of regular maintenance programs
to keep noise levels down by ensuring that both machin-ery
and its noise control features are kept in good condi-tion.
No matter which term the reader chooses to apply
to these noise control strategies— engineering controls
or administrative controls— the goal is the same: to
reduce employees’ noise exposures.
Controlling Employee Work Schedules
Work schedules may be modified in order to limit, or
control, the employees’ noise exposures. In a few special
situations the use of administrative controls has not
only significantly reduced employees’ TWAs but also
increased productivity by sharing a very demanding
33
task between two individuals. In one instance the oper-ator
[ TWA of 89 dB( A)] and oiler [ TWA less than 80
dB( A)] for a large dragline operation, who typically
worked 12- hour daily shifts, were both retrained and
allowed to change work positions every three hours.
Although the oiler’s salary had to be increased, the
resulting increase in productivity offset the cost of high-er
pay for the oiler, and both employees benefited from
reduction of their TWAs to less than 85 dB( A).
However, caution is advised in using administrative
options when they involve exposing a previously unex-posed
population [ TWAs less than 85 dB( A)] to poten-tially
damaging noise levels in order to reduce the
TWAs for a population that is already noise- exposed. In
general it is not good safety practice to increase the per-centage
of the workforce exposed to a known hazard.
Maintaining an Acceptable Maintenance Program
To prevent the noise produced by existing equipment
( newly purchased or modified by engineering controls)
from increasing significantly, a regularly scheduled equip-ment
maintenance program should be in place. It is com-mon
to control a noise problem by engineering means
only to return months later and find that the installed
noise mufflers, equipment enclosures, and vibration isola-tors
have failed to maintain the controlled level of noise
due to either sabotage, inappropriate equipment utiliza-tion,
or inadequate maintenance. Management has the
responsibility to ensure that equipment that has been
controlled for noise output is properly serviced and
utilized in order to maintain the controlled level of noise.
Management typically does not realize that equipment
that has been controlled for noise output must become a
part of a regular noise control equipment maintenance
program. Company engineers and noise control consul-tants
estimate that 2– 4 percent of the cost of noise control
will have to be spent yearly in maintaining the level of
noise reduction originally achieved.
34
It is important to require the active participation of
all involved parties ( such as equipment operators,
supervisors, and mechanics) in maintaining the produc-tion
equipment in a satisfactory condition. Management
directives and the regularly scheduled company educa-tion
program best achieve this goal.
Planning for Noise Control Purposes
A very effective use of administrative controls
involves long- term planning ( less than five years to
start of implementation) for a significantly quieter work
environment. It should be obvious to all by now, after
more than 20 years of OSHA, that in a high percentage
of noisy production environments there is no quick solu-tion
to the noise problem.
In these instances one solution is the purchase of new
equipment, or remodeling of existing equipment or facil-ities,
with sufficient guarantees of a noise- free or signif-icantly
reduced noise environment ( TWA reduced by 10
dB( A) or more). Notice that earlier a significant reduc-tion
in the noise environment was defined as 5 dB( A).
However, due to the problem of estimating noise envi-ronments
for new production facilities, a planned reduc-tion
of 10 dB( A) should guarantee at least a 5 dB( A)
reduction after equipment installation.
Noise Limits for Equipment Purchases and/ or
Modifications
A second effective use of administrative controls is
enforced equipment noise specifications for purchasing
new equipment or modifying existing equipment. Notice
that we emphasize “ enforced” because the clear tendency
in industry is for management to establish noise specifi-cations
that are regularly passed over by purchasing
agents for less expensive alternatives, regardless of the
cost differential.
35
Solving Noise Control Problems Using
In- House Personnel
The preceding discussions of noise controls have been
aimed primarily at defining the more obvious noise
problems. Once these problems have been defined then
management must decide the route to take in achieving
an engineering solution if appropriate. For the simpler
noise problems, in- house solutions are normally more
cost effective.
Purchasing quiet equipment to replace old machines or to outfit a new
facility can eliminate the noise exposure hazard.
To solve the minor noise problems in house it is nec-essary
to: ( 1) identify the individual who will find and
implement the solution and ( 2) give the individual the
necessary flexibility and authority. The experiences of
industrial personnel clearly show in- house staff do not
need professional training to solve simple noise prob-lems.
Nurses, audiometric technicians, and safety direc-tors
who have received the most elementary training in
noise control concepts have been successful at solving
such problems. Together with the lead mechanic, they
36
have controlled air exhaust noise by installing commer-cially
available mufflers. They have controlled HVAC
fan system noise by purchasing and installing in- line
commercially available noise attenuators. They have
controlled motor noise resulting from improper vibra-tion
isolation by installing appropriate commercially
available mechanical isolators.
Company personnel should not believe that without the
results of the noise control survey, a noise problem cannot
be solved without expensive outside consulting services.
For the more difficult noise problems, however, some type
of outside consultation is almost always necessary. Private
firms specialized in noise abatement offer consultation
services. Additionally, consultation is available through
the Bureau of Consultative Services, Division of Occupa-tional
Safety and Health, North Carolina Department of
Labor. ( See the inside back cover of this publication for the
address and telephone number.)
Sources of Information
For immediate information concerning possible noise
control options, management has several possible
sources including the resource staff of the North
Carolina Department of Labor, trade associations,
insurance carriers, and extension departments at the
local technical college or university. In addition to these
sources, there are chapters and articles, plus several
relatively easy- to- read textbooks ( see References, items
6– 10) and one free journal that publishes an annual
summary of all the manufacturers of noise and vibra-tion
control products ( see Resources, item 3).
37
Checklist for Noise Controls
Engineering noise control survey completed.
Dominant production noise sources identified.
Contributing equipment noise sources identified.
Equipment noise purchase specifications exist.
Noise control maintenance program exists.
HCP education phase includes engineering
controls.
New facility planning includes noise control.
Solution of simple noise problems documented.
38
6
Hearing Protection
Hearing protection devices ( HPDs) are the first line of
defense against noise in environments where engineer-ing
and/ or administrative controls have not reduced
employee exposures to safe levels. HPDs can prevent
significant hearing loss, but only if their utilization is
carefully implemented and supervised. Employees will
not achieve adequate protection if various HPDs are
simply placed onto the tool crib shelf, with the choice of
style and size left up to the employee.
For more information about hearing protection, see
References, items 4 and 11– 12, and Resources, item 4.
Organizing the HPD Phase for Success
HPD effectiveness cannot be achieved without the
enthusiastic and diligent efforts of those who select, fit,
issue, and reissue the protectors. Management must
choose capable and interested personnel to handle the
HPD phase. Those selected should be provided with the
knowledge they need to do a good job. Working with the
employee in selecting optimal HPDs and training the
employee to wear and care for HPDs are much more
complicated tasks than dispensing safety glasses, for
example. Therefore, those responsible for HPDs need
detailed education from the HCP supervisor, from
attending a CAOHC course, or from materials and
workshops sometimes provided by HPD manufacturers
and associations concerned with hearing conservation.
HPDs will not protect employees unless their proper
utilization is absolutely enforced as a condition of employ-ment.
Many companies have written disciplinary rules for
failure to wear HPDs, but they are never implemented.
For the HCP to be effective, management must set the
39
same priority on HPD utilization as on the use of all safety
equipment and then back it up with action: the employee
either wears HPDs in required areas or goes home.
Types of HPDs
Earplugs
The most popular HPDs are earplugs, which are
inserted into the ear canal to provide a seal against the
canal walls. Preformed earplugs are made of flexible,
vinyl materials and often come in different sizes to fit
different sizes of ear canals. Formable earplugs are
made of materials that can be manipulated to conform
to the shape of the wearer’s ear canals. The best
formable earplugs are made of foam, which is com-pressed
for insertion into the ear canal, then expands to
fill the canal and seal against its walls.
Earmuffs
Sometimes called circumaural HPDs, earmuffs
enclose the entire external ears inside rigid cups. The
inside of the muff cup is lined with acoustic foam ( which
must not be removed), and the perimeter of the cup is
fitted with a cushion that seals against the head around
the ear by the force of the headband. In most industrial
environments earmuffs are less popular than earplugs,
but they can provide reliable protection.
Semi- Aurals or Canal Caps
These HPDs are small stoppers that seal against the
entrance to the ear canal by the force of a band worn
under the chin or behind the neck. They generally pro-vide
less protection than earplugs or earmuffs. They are
most suitable for short- term use, as they are less com-fortable
than other HPDs for all- day wear.
40
41
Formable foam earplugs
expand to fit ear canals of
different sizes and shapes.
Preformed earplugs may
come in from one to five
sizes to fit different ear
canals.
Earmuffs cover the ear to
block out noise.
Semi- aural HPDs or canal caps are
convenient for brief periods of
noise exposures.
Hearing Protector Attenuation
All HPDs attenuate noise by creating a seal that pre-vents
sound from entering the ear. Earplugs mainly
seal against the wall of the ear canal, while semi- aurals
seal against the entrance to the ear canal or its outer
edge, and earmuffs seal against the head all around the
external ear. In each case the amount of sound reduc-tion
achieved depends largely on the completeness of
the seal— any air leaks will allow some sound to bypass
the HPD.
The maximum achievable attenuation is limited by
the bone- conducted sound that results when sound
vibrates the skull. However, bone- conducted sound
transmission is not important for industrial environ-ments
compared to the effect of whether the HPD is fit-ted
properly and used correctly. In practice, when
employees do not receive adequate protection from their
HPDs, it is because they do not achieve an adequate
seal. This may happen because the HPD does not fit
properly ( the HPD is the wrong size or design for the
individual) or is not used correctly by the employee ( due
to inadequate training or carelessness).
The Noise Reduction Rating ( NRR)
HPD manufacturers publish attenuation data for
their products based on idealistic laboratory measure-ments.
The NRR shown on the label of the HPD pack-age
is intended to give a single- number rating of the
laboratory attenuation across a range of frequencies.
The NRR is subtracted from the employee’s noise expo-sure
to indicate the maximum exposure reduction that
could be attained if the employee had similar physical
characteristics as the laboratory subjects and could
wear the product in the same way as the laboratory
subjects.
The NRR is designed to be subtracted from the
C- weighted sound pressure level to give the A- weighted
level under the HPD:
[ Noise level, dB( C)] – [ NRR] =
[ estimated exposure, dB( A)]
If only A- weighted exposure is known, then a correc-tion
factor of 7 dB must be subtracted from the NRR:
[ Noise level, dB( A)] – [ NRR – 7] =
[ estimated exposure, dB( A)]
The 7- dB correction factor is needed with A- weighted
levels because the dB( A) value gives no indication of
42
whether the energy in the noise environment is predom-inately
low- frequency or high- frequency, and HPDs pro-vide
less protection at lower frequencies. Most dosime-ters
predict only noise dose or equivalent TWA values
based on A- weighted sound pressure levels. However, if
the sound surveyor measures both dB( A) and dB( C)
levels with a sound level meter, then the average “ C
minus A” difference for the noise environment can be
used as the correction factor in place of 7 dB. In high-speed
textile spinning, for example, “ C minus A” differ-ences
ranging from 2 to – 1 dB have been measured.
Real- World Attenuation
Although the NRR is a readily available number that
appears as if it should allow the HPD selector to decide
whether a protector is adequate, it is flawed by the labora-tory
test conditions used to obtain it. Real- world users do
not achieve the amount of attenuation indicated by the
NRR. In general, HCP personnel can count on properly
trained and motivated HPD wearers receiving about 50
percent of the NRR value in attenuation. Very motivated
users can achieve better results. ( See References, item 12).
The NRR cannot even be used to rank the real- world
effectiveness of HPDs. Studies in which employees were
pulled off the job to have their actual HPD attenuation
measured have shown that the attenuation achieved
with different HPDs gave a different rank from their
NRRs. Products that are more “ goof- proof” ( foam
earplugs and earmuffs) provided higher real- world
attenuation than other HPDs ( see References, item 12).
Because the NRR is not a realistic indicator of the
attenuation that wearers achieve, HCP personnel should
not use the NRR as a significant criterion for evaluating
HPDs. Comfort, convenience, and compatibility with the
working environment ultimately determine the protec-tion
an employee will receive from a hearing protector,
since the effective attenuation of an unworn HPD is zero.
43
Purchasing Appropriate HPDs
It is essential to select and keep in stock a sufficient
choice of HPDs appropriate to the work environment
and the wearers’ needs. Generally an adequate selection
would include three types of earplugs, two styles of ear-muffs,
and one semi- aural device.
The choice of HPDs should be made by the HCP per-sonnel,
based on characteristics of the work environ-ment
and real- world HPD performance as well as the
preferences of the employees. The purchasing depart-ment
must not be allowed to overrule the HPD selec-tion.
Management should give HCP personnel the
authority to obtain the HPDs they feel are best for the
company’s workforce. The factors that should be consid-ered
in choosing HPDs the company will stock are dis-cussed
in the following paragraphs.
Real- World Attenuation
Because most employees have noise exposures below
a TWA of 95 dB( A), they only need 10 dB of real- world
attenuation. Most HPDs can provide this much protec-tion,
if properly fitted and correctly worn. Higher
employee TWAs require more careful HPD selection,
and only the protectors with the best real- world attenu-ation
( earmuffs or foam earplugs) are recommended for
TWAs of 100 dB( A) or above.
Comfort
Employees will not wear uncomfortable HPDs, so the
goal of fitting is to find the most comfortable HPD that
gives adequate protection for the environment. Because
44
The best HPD is the one
the employee will wear
consistently and correctly!
no single HPD suits all wearers, several choices should
be available. The employee should be allowed to select
his or her preferred HPD as long as the issuer confirms
that the fit is adequate for the required attenuation.
Convenience
Employee acceptance of HPDs depends on practical
factors such as:
✦ Ease of correct positioning considering physical
limitations of the wearer ( such as finger size or
strength, arthritis)
✦ Speed and ease of HPD removal and repositioning
✦ Simplicity of carrying or storing during work breaks
✦ Compatibility with other safety gear ( masks, hard
hats)
✦ Suitability for job tasks ( crawling in tight spaces,
strenuous physical activity, repetitive head move-ments)
✦ Practicality in the physical environment ( for exam-ple,
considering heat, dirt, chemicals)
Each employee needs to be shown how to insert earplugs or wear ear-muffs
properly to achieve a good seal and adequate protection.
45
Communication Needs
Select a HPD that will allow the employee to commu-nicate
as required in the workplace noise environment.
For normal- hearing employees, this is usually not a
problem since HPDs improve speech discrimination in
noise above 90 dB( A) by reducing distortion in the ear
from high sound levels. However, for workers with pre-existing
hearing loss, HPDs often make communication
more difficult by reducing speech- sound information to
below their hearing thresholds. Hearing- impaired
employees who must receive detailed face- to- face
instructions may prefer earmuffs so that they can lift
up the earmuff cup to hear speech, or plugs with mini-mal
attenuation may improve reception of speech as
well as auditory warning signals. Hearing- impaired
employees may also benefit from the new HPDs
presently being developed that exhibit flat attenuation
across the frequency spectrum. These HPDs provide
less reduction than regular HPDs of the high- frequency
sounds that are affected most by hearing loss.
Employee Input
HCP personnel need to solicit employee opinions
about various HPD products. This can be done by con-ducting
wearer evaluation trials, by asking for employ-ee
feedback in safety meetings and in the break room or
cafeteria, and by questioning individuals when HPDs
are reissued or when the annual audiogram is adminis-tered.
HCP personnel should be aware of new HPDs
that might be suitable additions to or replacements for
the HPD choices currently carried in stock. When
employees ask about products they have seen, if practi-cal,
the HPD issuer should investigate these options.
46
Maximizing the Effectiveness of HPDs
in Actual Use
The attention paid by the HPD issuer to the following
factors will determine how much real- world protection
employees receive from their HPDs.
Correct Fit
HPDs offer little or no protection if they do not form a
seal to block out sound. All HPDs must initially be fitted
by a trained issuer. Earplugs must be fitted separately in
each ear, as an individual’s two ear canals may differ in
size or shape. Because none of the “ universal- fit” plugs
can actually fit every individual, even one- size earplugs,
including foam earplugs, must be checked for proper fit
in both left and right ears. Pamphlets about selecting
and fitting HPDs are available from National Hearing
Conservation Association ( see Resources, item 6).
Good HCPs always stock premolded plugs in a full
range of sizes to suit extra small and extra large ear
canals. Before inserting an earplug into the employee’s
ear, the fitter must visually cheek the ear canal for excess
wax or obvious abnormal conditions that would require fit-ting
to be delayed until the problem is corrected. The fit of
earmuffs also must be checked for each wearer to make
sure that the earmuff cushion seals against the head all
around the ear, and that the outer ear ( pinna) can fit
inside the cup ( the cushion must not rest on the pinna).
Training Users
Each HPD wearer must receive specific instructions on
how to wear and care for the HPD issued. To ensure that
47
There is no such thing as
a “ universal- fit” HPD!
the employee can insert or place the HPD correctly, the
fitter should watch while the individual user demon-strates
how to put on the HPD correctly. If the employee’s
initial attempt is inadequate, the fitter should reinstruct
and have the worker practice in the fitter’s presence until
proper placement is achieved. Employees must be con-vinced
that they will not receive adequate protection
unless they correctly wear and maintain their HPDs. The
employee needs to know the signs of HPD deterioration
that indicate it is time to get a replacement. Each year
the employee should be asked to bring his or her HPDs to
the audiometric evaluation so that the fitter can inspect
them for wear, reevaluate the fit, and check that the
employee can still place them correctly.
Responding to Wearer Questions and Complaints
HPD issuers must be open to employee concerns.
Issuers should seek answers to employees’ questions
and work individually with employees who find it diffi-cult
to wear HPDs because of discomfort or the inability
to communicate adequately while wearing them.
Controlling the HPD Replacement Process
HPD reissuers need to maintain strict control of
replacements so that employees are reissued only the
style and size of HPD indicated on the fitting record.
Employees who wish to change HPD type or size must
return to the fitter for refitting.
Replacing HPDs Regularly
New HPDs should be routinely issued to each wearer
on a schedule appropriate for the type of HPD being
worn. An aggressive replacement procedure will pre-vent
employees from retaining HPDs that have lost
their effectiveness. At the same time HCP personnel
can detect altered HPDs and reeducate the employees
who made alterations. Some key individuals periodical-ly
set up an HPD replacement station at the plant exit
during shift changes as an extra reminder.
48
Monitoring HPD Utilization
Front- line supervisors and production department
heads need to perform regular checks to ensure that
employees are properly wearing their HPDs. Employees
who do not cooperate with the mandatory HPD utiliza-tion
policy must receive reeducation and meaningful
disciplinary actions, eventually culminating in dis-missal
for repeated offenses. At the same time, consis-tent
HPD users should be rewarded for their perfor-mance
through recognition for departments with good
utilization records and by praise for individual wearers.
Motivating Employees to Wear HPDs
Effectively
Ultimately, the employee who wears the HPDs is per-sonally
responsible for achieving and maintaining protec-tion
from noise through the proper use of HPDs. However,
the employer must educate and motivate the employee to
take this active part in the HCP. The key individual and
other HCP team members should strongly consider
employees’ input when selecting the HPDs to be stocked,
as well as when finding a suitable protector for an indi-vidual.
Employees need clear, understandable informa-tion
to help them appreciate that they will be protected
from developing hearing loss only if they consistently and
correctly wear HPDs that are fitted properly.
Identifying Satisfactory HPDs
The employee and the fitter need to work together to
select a product that will be comfortable and convenient
enough for the worker to wear it consistently. The
employee who has received proper education will under-stand
that some initial discomfort is expected during
the breaking- in period when getting used to HPDs. If
the employee still encounters significant discomfort or
interference with job tasks after one to two weeks of
wearing a new HPD, then the wearer should return to
the fitter to request another type.
49
Wearing HPDs Correctly and Consistently
Ultimately employees must accept the responsibility
to reduce their noise exposure by faithfully and properly
wearing HPDs both on and off the job. Intermittent or
incorrect HPD use will not prevent the development of
noise- induced hearing loss. The department supervisors
can ensure that all employees in HPD- required areas
are wearing HPDs, and the HPD fitters can spot- check
in each department for actual correctness of HPD fit and
placement. Annually, at audiogram time, each employee
should be retrained in proper HPD fitting, use, and care.
Caring for and Replacing HPDs
Employees need specific instructions as to how to: wash
their HPDs, store them in cases or safe places to prevent
damage, inspect them for signs of wear and tear, and seek
replacements when deterioration occurs. Employees must
be taught that achieving good protection depends on keep-ing
the HPDs in good condition. Worn- out or intentionally
altered HPDs will not provide adequate attenuation.
Demonstrating Management Support
Managers must demonstrate support for HPD utiliza-tion
and emphasize its importance by:
✦ Wearing HPDs each time they enter an area with
either a voluntary or mandatory HPD wearing pol-icy
( no matter for how brief a time the managers
are in the area)
✦ Establishing a policy of mandatory HPD utilization
✦ Making HPD utilization enforcement part of the
basis for performance ratings of the front- line
supervisors and production department heads
✦ Providing a mechanism for regularly praising or
rewarding employees who wear HPDs correctly
and consistently
50
✦ Rating the performance of all personnel responsi-ble
for any aspects of HPD utilization enforcement,
fitting, issuing, and replacement
✦ Directing that HPDs be made available to employ-ees
for off- the- job noise exposures so that hearing
will be protected around the clock
✦ Purchasing equipment to allow HPD issuers to
monitor the field performance of HPDs as actually
used by individuals
✦ Scheduling regular meetings among the HPD fit-ters
and issuers, the reissuers, and the supervisors
who enforce utilization on a daily basis
Shooting is one of the most common causes of off- the- job noise-induced
hearing loss, but hearing protectors are very effective against
gunfire noise.
51
Checklist for Hearing Protection
HPD utilization in required areas is strictly and
consistently enforced.
Comfort, practicality, and real- world attenua-tion—
not the NRR— are the primary criteria for
selecting which HPDs will be stocked.
Each employee is individually fitted with HPDs
and trained in their proper use and care.
Fit is checked for all types of HPDs, including ear-muffs
and single- size earplugs.
A minimum of two earplugs ( one in multiple sizes)
and one earmuff are available for selection, but
preferably three plugs, two muffs, and one semi-aural.
HPDs are replaced on a regular basis.
HPD reissuers distribute only the type of HPD fit-ted
to each employee; to change types or sizes the
employee must return to the fitter.
Each employee’s HPDs are rechecked during the
audiometric evaluation for condition, fit, and cor-rect
placement.
Employees are given HPDs to take home for use
during off- the- job noise exposures.
52
7
Audiometric Evaluations
The audiometric evaluations phase of the HCP ties
together all the other phases by indicating whether the
program’s goal is being achieved: prevention of on- the- job
hearing loss. If the HCP is not effective, the result will be
seen as worsening hearing thresholds for employees, as
well as a higher percentage of the noise- exposed popula-tion
showing an OSHA standard threshold shift ( STS).
One consequence is an increase in the company’s poten-tial
liability for compensable occupational hearing loss.
When audiograms detect temporary threshold shift,
early permanent threshold shift, or progressive noise-induced
hearing loss, the HCP personnel are alerted to
take swift actions to halt the loss before the employee’s
hearing shows a significant deterioration. Because
noise- induced hearing loss typically occurs so gradually,
the affected individual may not notice the slow change
until a large threshold shift has accumulated. Audio-metric
monitoring can identify individuals who are
inadequately protected so that they can be retrained
and/ or given better HPDs and extra motivational atten-tion
to prevent further loss.
However, audiometric evaluations cannot provide
reliable data to guide intervention unless they are con-ducted
under adequate quality standards and the
results are appropriately evaluated and meaningfully
communicated to the employee. For more details about
the audiometric phase, see References, items 13– 15.
Management Support Needed for Quality
Managers must support the audiometric evalua-tions
phase by funding quality services. Because
audiometry requires a substantial investment of
53
money and personnel time, it is cost- effective to allo-cate
enough resources to ensure that the desired ben-efits
are obtained from audiometric monitoring.
Otherwise, the money is simply wasted on deficient
services that do not serve their intended purpose of
alerting HCP personnel to take actions that will pre-vent
hearing loss.
54
Normal Audiogram
and Degrees of Hearing Loss
SLIGHT
MILD
MODERATE
MODERATELY SEVERE
SEVERE
PROFOUND
– 10
0
10
25
40
55
70
85
100
Hearing Threshold Level, dB
Frequency, Hertz
500 1000 2000 3000 4000 6000
Low Pitched
Sounds
High Pitched
Sounds
The audiogram shows hearing thresholds for tones at dif-ferent
pitches or frequencies. Normal thresholds fall within
the unshaded area of the chart. If noise- induced hearing
loss begins to develop, the thresholds for the higher fre-quencies
( 3,000– 6,000 Hz) will start to fall into the shaded
areas.
• • • • • •
In- House versus Contracted Services
Managers may choose to contract for employee audio-grams
to be performed by an external source ( a mobile
testing contractor or a local clinic). Alternately, manage-ment
may purchase audiometric equipment and train
internal personnel to perform audiograms under the
supervision of an audiologist or qualified physician. The
choice depends on factors including the company’s phi-losophy
about safety and health, as well as its size and
geographical location. Our experience indicates that the
audiometric phase will be much more effective in moti-vating
employees if their audiograms are performed
and discussed with them by in- plant HCP personnel. If
external services are used, it is critical that manage-ment
assign responsibility to the on- site key individual
for making sure that quality services are obtained and
for using the audiometric results to motivate employees.
Well- Qualified Personnel to Perform Audiograms
The audiometric technicians should hold current
CAOHC certification as occupational hearing conserva-tionists.
Additionally, all technicians should use consis-tent
testing methods under the supervision of an audi-ologist
or qualified physician.
Adequate Time Allowed to Complete Evaluations
If the audiogram session is to achieve its potential for
motivating the employee about hearing conservation,
there must be adequate time for that purpose. The tech-nician
needs sufficient time to obtain auditory history
information, inspect HPD condition and fit, properly
instruct the employee, carefully administer the audio-gram,
briefly explain the results to the employee, and
document the findings. When the technician is too hur-ried
to do more than give a rapid screening audiogram
and herd the employee out the door, the worker correctly
perceives that the testing is performed only for OSHA
compliance without any sincere interest in protecting
55
hearing. In this case the employee will usually lose moti-vation
to participate in the HCP.
Obtaining All Needed Information
The OSHA regulations do not require measurement
of hearing thresholds at 8,000 Hz or the documentation
of auditory history information ( details about the
employee’s off the job noise exposures, medical condi-tions
affecting hearing, the presence of ringing in the
ears, and other associated information). However, the
wise employer will include both of these features in
employees’ audiometric evaluations because they allow
the reviewer to interpret the audiogram results with
more confidence and may eliminate a number of costly
medical referrals. The 8,000 Hz thresholds assist the
reviewer in distinguishing between age- related hearing
change and noise- induced hearing change. The auditory
history information assists the reviewer in deciding
whether observed hearing change is probably related to
on the job noise exposures, or whether off- the- job causes
may have contributed.
Regular Schedule of Audiometric Monitoring
For maximum protection of the company and employ-ees,
audiograms should be performed at pre- employ-ment
or prior to initial assignment to a noisy work area.
Thereafter, audiograms should be performed annually
for as long as the employee is assigned to a noisy job ( or
twice a year during the first two years of exposure for
workers with TWAs over 100 dB( A)). The company
should also perform an audiogram when the employee
is reassigned out of a noisy job and at the termination of
employment.
Many companies have found it is desirable to give
audiograms, as a health screening benefit, every one to
three years to employees without on- the- job noise expo-sure.
Annual audiometric results for nonexposed
employees also serve as a control group when using
56
audiometric data base analysis to evaluate the HCP’s
effectiveness, as discussed in the final section of this
publication.
Careful Choice of a Professional Reviewer
Management should ensure that the program super-visor
who reviews employees’ audiograms is a well- qual-ified
professional with specific training and experience
in the area of industrial hearing conservation. Such a
choice will benefit the employer as well as the employ-ees,
as an experienced audiologist or physician is less
likely to mistake nonoccupational loss as being job-related.
Feedback and Follow- up
The audiometric session is the greatest opportunity
to motivate employees concerning hearing conservation.
Management should allow an extra two minutes for the
audiometric technician to give the employee simple,
brief remarks about his or her hearing status immedi-ately
after the audiogram is completed to praise the
worker or warn that better HPD utilization is needed.
All employees ( not just those with threshold shifts)
should receive written feedback from the professional
reviewer. When the reviewer points out potentially
noise- induced hearing changes, company personnel
need to take decisive follow- up actions. These actions
include individual counseling, refitting and retraining
for HPD utilization, encouraging the employee to wear
HPDs during off- the- job noise exposures, and more
careful supervision of on the job HPD use. When the
reviewer indicates that the shifts appear unrelated to
noise exposure, the employee should be urged to seek
otological/ audiological evaluation and treatment. If
audiograms are filed and forgotten rather than used to
guide follow- up actions, then the audiometric phase
simply documents hearing loss as opposed to helping
prevent it.
57
Quality Control Responsibilities of
Audiometric Technicians
The accuracy and usefulness of the audiogram results
depend on the care and attentiveness of the audiometric
technicians.
Maintaining Test Equipment and Environment
Audiogram accuracy depends on the audiometric
technicians performing and documenting daily calibra-tion
checks and self- listening checks of audiometer
function. If an electro- acoustic blockhead device is used
to check calibration of audiometer output levels, the
technician must still listen through the earphones for
signal distortion or erratic responses that the device
cannot detect. A log of biological and/ or electro- acoustic
output checks and listening checks of audiometer func-tion
should be maintained.
To measure thresholds accurately for employees with
0- dB hearing levels and to ensure that company audio-grams
are acceptable for legal purposes ( such as workers’
compensation claims), the test room must be quiet
enough to meet ANSI standard S3.1- 1991. That standard
requires lower background levels than the OSHA Hearing
Conservation Amendment. The technician should periodi-cally
check and document background levels.
Acoustic and exhaustive audiometer calibrations should
be scheduled regularly, but calibration services should not
be allowed to adjust the audiometer unless it fails to meet
calibration tolerances. Unnecessary annual adjustments
typically add seesaw variability to the audiometric data,
interfering with the interpretation of both individual and
group hearing trends. If audiometer adjustments must be
made because tolerances are exceeded, the calibration
company must be required to provide both preadjustment
and post- adjustment measurements so that the size and
direction of changes will be documented.
58
Another source of measurement variability can be
prevented by using the same audiometers consistently.
Technicians should not switch back and forth between
types of audiometers ( manual, self- recording, and
microprocessor audiometers).
Using Consistent Instructions and Testing Methods
All audiometric technicians should use the same
standardized testing method under the supervision of
an audiologist or qualified physician. If technicians do
not place the earphones carefully to line up the ear-phone
speakers with the employee’s ear canals, then the
measured thresholds may be in error; therefore, never
allow employees to place the earphones themselves.
When technicians differ in their response instructions
to employees or their signal presentation and threshold
recording methods, the excess variability in threshold
measurements interferes with interpretation of hearing
trends. It is very important to instruct employees to lis-ten
carefully and respond to the faintest tones they can
just barely detect— rather than waiting until tones are
loud and clear before responding. ( The wording of the
instructions can be adjusted to whatever vocabulary
seems most meaningful to the employees, but this con-cept
of listening for faint tones must be communicated.)
Because hearing thresholds may improve over time, the
audiometric technician must try to measure the best
thresholds for the employee, not just duplicate the
results of the last test.
Maintaining Complete Records
The audiometric record should indicate the specific
equipment used, calibration date, the name of the tech-nician,
the date and time of the test, and the threshold
values obtained. The technician’s judgment of the sub-ject’s
response reliability, the HPD inspection results
and refitting or reissuing record, the employee’s TWA,
and the technician’s comments should also be recorded.
59
The professional reviewer’s recommendations and docu-mentation
that follow- up actions were carried out
should be documented too.
Annual audiometric evaluations monitor the employee’s hearing
thresholds. If noise- related hearing changes are detected, counseling
and HPD retraining may help achieve better protection.
Scheduling Audiograms
The audiometric evaluations should be scheduled in
close coordination with production supervisors in order
not to disrupt production more than necessary. If super-visors’
needs are ignored, the supervisors will be less
likely to fulfill their HCP responsibility of monitoring
HPD utilization. To minimize the disruptive effect on
departments and to ensure that employees who are
transferred among departments do not accidentally
miss their annual audiograms, it is often useful to
schedule audiograms in the employee’s birth month.
Participation in annual audiometric evaluations should
be a condition of employment, not a choice.
60
The baseline audiogram should be administered
when the employee has not been exposed to noise for
the preceding 14 hours. However, annual audiograms
should be administered during the workshift, not before
it, so that the results will detect any temporary thresh-old
shifts in hearing that may be occurring in employees
who are not adequately protected.
Using the Audiogram Session to Best
Advantage
The annual audiogram is often the only predictable
time during the year when the individual employees
have the opportunity for a one- to- one conversation
about hearing conservation and their own hearing sta-tus.
This time is the best chance to motivate workers to
protect their hearing. Whether the technicians are
external ( contract) personnel or internal ( staff mem-bers),
they absolutely must demonstrate enthusiasm for
hearing conservation and sincere interest while per-forming
audiograms and giving feedback to employees.
Auditory History Information
The OSHA regulations do not require maintenance of
auditory history information ( documentation of the
employee���s past noise exposures in the military and in
previous jobs, the employee’s off- the- job noise exposures
such as gunfire or use of power tools, and the employ-ee’s
ear- related medical history). However, it is in the
employer’s best interest to record these data for better
interpretation of the employee’s audiometric results and
for protection against future hearing loss compensation
claims. Updated history information allows the profes-sional
reviewer to make recommendations with more
insight and confidence concerning probable causes for
threshold shifts. In addition, the history questions
remind the employee that off- the- job factors influence
hearing status.
61
Checking HPDs at Time of Audiogram
As previously discussed in the HPD section, the
audiometric technician should check the condition and
fit of the employee’s HPDs, change them if needed, and
reinstruct the wearer.
Immediate Feedback about Hearing Trends
The professional who supervises the audiometric
technician can provide guidelines for the technician’s
comments about employees’ hearing as soon as they
step out of the audiometric booth. That is when they are
most interested in their hearing and most receptive to
suggestions. If hearing thresholds have remained sta-ble,
praise the employee for a job well done. If thresh-olds
appear to be worsening, advise the employee of the
need to determine the causes of the hearing change. For
example, the causes might be medical problems or inad-equate
use of HPDs on or off the job. Note that the pro-fessional
reviewer will provide more detailed written
feedback about the hearing changes.
Following up on Audiometric Results
Every audiometric record must be reviewed to classi-fy
the hearing trends and determine whether other
actions are needed.
Careful Audiogram Review
The supervising professional may set up procedures
for the technician to follow when reviewing routine
records ( those with normal hearing and no shifts or
improvements) and when preparing employee feedback
notices. Alternately, the company may find it easier to
have the professional review the routine records as well
as the problem audiograms. The reviewer needs to look
for significant improvement threshold shifts at any test
frequency ( not just OSHA standard threshold shifts)
and look at audiogram patterns indicative of possible
62
otological pathology. Significant shifts would include a
change of 15 dB at any frequency that is confirmed as
being persistent on a retest, or a change of 20 dB
( whether confirmed or not).
Prompt Meaningful Feedback
The reviewer ( or technicians under professional
supervision) should provide each employee written feed-back
describing the worker’s hearing status in terms of
three aspects:
1. Comparison to the expected age- effect hearing lev-els
for the worker’s age/ sex/ race group and the hearing
ability needed for unimpaired communication
2. A description of the amount of change seen in the
current audiogram compared to past results and the
designated reference baseline
3. Recommendations, including praise for stable
hearing, warnings to use HPDs more carefully on and
off the job if hearing changes are observed, and sugges-tions
to seek medical attention or further audiological
evaluation
Taking Appropriate Follow- up Actions
OSHA regulations specify required follow- up actions
for OSHA STS ( a change of 10 dB in the average
63
All employees need feedback
not just those with OSHA STS!
Audiograms don’t prevent hearing loss
but feedback and follow- up can!
thresholds at 2,000, 3,000, and 4,000 Hz in either ear
after optional corrections for aging). But in effective
HCPs, aggressive follow- up for beginning hearing shifts
will prevent losses from progressing into OSHA STSs.
In an excellent HCP the employee with beginning shifts
will receive a written warning from the professional
reviewer and face- to- face counseling from on- site HCP
personnel based on the reviewer’s comments. Similarly,
there should be reevaluation of HPD adequacy, retrain-ing
in HPD placement, and extra supervision in on- the-job
HPD utilization for such an employee. A retest
audiogram may be given to see if the shifts persist or
disappear. Individuals with potential medical ear condi-tions
will be counseled by the employer to seek medical
evaluation and treatment or possibly be sent for treat-ment
at company expense.
Immediate feedback about the audiogram results can motivate the
employee to protect hearing on and off the job.
64
Educating Employees to Take
Responsibility
As employees become familiar with the audiometric
evaluation process, understand their audiogram results,
and learn how their everyday habits in HPD utilization
can affect their hearing trends, they will be encouraged
to take the lead in protecting their own hearing on and
off the job. No matter how much effort the employer
puts into the HCP, it is impossible to inspect whether
each employee is wearing HPDs adequately each day.
Eventually the individual worker must accept responsi-bility
for following through with good hearing protection
habits. The best tool the hearing conservationist has to
motivate individuals about protecting their hearing is
to counsel them about their audiogram results.
Checklist for Audiometric Evaluations
Audiometers are in good operating condition.
Audiometer calibration is not adjusted unless it is
out of tolerances, and both pre- adjustment and post-adjustment
readings are permanently recorded.
Audiometric technicians use consistent testing
methods under professional supervision.
Technicians instruct employees to listen carefully
and respond to the faintest tones they can detect.
Employees’ auditory history information is updat-ed
annually and provided to the audiogram
reviewer.
Employees receive immediate feedback from the
audiometric technician about audiogram results
as related to HPD use.
65
Employees receive written feedback from the
audiogram reviewer about:
• hearing status compared to normal for age
• hearing change over time
• recommendations for better protection on and
off the job, or for medical examination or treat-ment
if appropriate.
The audiogram reviewer looks for significant
shifts at any frequency, not just for OSHA STSs.
Audiogram reviewers revise employees’ reference
baseline thresholds for threshold improvement as
well as for persistent worsening.
HCP personnel follow through with counseling
and HPD retraining for employees with hearing
change.
66
8
Making Sure
That the HCP Works
The Team Approach
Now that you have reviewed all five phases of HCPs,
take another look at figure 1 and consider the impor-tance
of teamwork in achieving the goal of preventing
hearing loss on the job. No single phase of the HCP
can work effectively in isolation from the others. Many
people are involved: foremen, tool crib clerks, safety
officers, audiometric technicians, nurses, personnel
directors, industrial hygienists, engineers, audiolo-gists,
and physicians. No single discipline can claim
superior ability to run the HCP: the program depends
on the cooperation of many people, under the leader-ship
of the key individual. The key individual can be
anyone with the interpersonal skills and managerial
know- how to coordinate the contributions of these
diverse personnel toward preventing hearing loss. The
key individual is the catalyst who makes the HCP
work by maintaining communication among the team
members to achieve a unified HCP.
Documentation and Recordkeeping
When the OSHA inspector visits, the only way the
company can demonstrate that the HCP is satisfactory
is through adequate documentation of the five phases.
Some people actually refer to recordkeeping as a sixth
phase, but recordkeeping is an integral part of each
phase, not a separate activity. For example, the audio-metric
phase depends on cumulative records to show
hearing changes over time. It also depends on records of
67
auditory history information, employee noise exposure,
and HPD fitting and reissuing to evaluate whether
threshold shifts may be work- related. In addition to the
legal documentation it provides, good recordkeeping is
helpful in monitoring the program and sharing informa-tion
among HCP team members. The key individual
should assign responsibility to HCP team members for
maintaining the records associated with their duties
and should ensure that the records are accessible. A list
of the needed records is shown as table 4, and further
details are provided in References, items 16– 17.
Recording Hearing Loss on the OSHA
200 Form
Occupational hearing loss is recorded on the OSHA
Form 200 either as an occupational illness ( for gradual
hearing loss) or as an occupational injury ( for sudden
traumatic hearing loss). In North Carolina and several
other state OSHA plans, the amount of work- related ( if
work- related) hearing change that must be recorded is
the OSHA standard threshold shift or STS ( a change in
either ear from baseline of 10 dB in the average of hear-ing
thresholds at 2000, 3000, and 4000 Hz, with option-al
corrections for aging). In states under federal OSHA
plans, a work- related change of 25 dB in the average of
thresholds at 2000, 3000, and 4000 Hz must recorded.
However, since 1996 federal OSHA has been consider-ing
changing this 25- dB value to a smaller amount of
shift, so this requirement may be updated. Numerous
professional associations have supported logging work-related
age- corrected shifts of 10 dB ( see docket testi-mony
for 1996 OSHA hearings on recordability, as well
as the AIHA position statement published in the
American Industrial Hygiene Association Journal, vol.
57, pages 661– 662, 1996).
68
Table 4
Documentation Guidelines for the HCP
69
A. Records Specified in OSHA’s Hearing Conservation Amendment
1. Noise exposure measurements
• Detailed survey report must include complete list of instru-ments
used in survey, calibration, measurement positions,
tables of sound level measurements, and TWA calculations
List departments or employees with TWAs of 85 dB( A) or over
• For OSHA retain 2 years or until new sound survey
• Keep indefinitely for workers’ compensation purposes
2. Documentation of engineering/ administrative noise controls
• results of engineering sound surveys
• installations completed and noise reduction achieved
• regular maintenance of machinery and controls
3. Documentation of annual educational programs, including:
• content of presentation
• names of presenters
• list of employees who attended
4. Documentation of hearing protection phase of HCP:
• date of initial HPD fitting of each employee
• brand and size of HPD fitted ( in each ear if appropriate)
• employee’s signature for training in HPD use and care
• documentation of employer’s supervision of correct HPD use
such as walk- through checks of utilization
• NRR and TWA calculations showing HPD adequacy
5. Employee’s audiometric records, including:
• name, age, job classification, and TWA exposure
• date of audiogram and name of audiometric technician
• audiometer model SN and date of its last calibration
• Retain for duration of employment for OSHA
• Keep indefinitely for workers’ compensation
6. Supporting records for audiometric phase of HCP:
• technician’s certification credentials
• audiometer make, model, and serial number
• audiometer acoustic and exhaustive calibration records
• biological calibration check records of audiometer
• background sound levels in audiometric test room
Assessing Your HCP
The most basic form of program assessment is to use
the checklists provided in this booklet to see whether all
the bases have been covered. Have all the tasks been
accomplished? For example, the key individual might
discover that a group of employees did not attend an
educational program or missed their annual audio-grams.
Just as important is whether the more subjective
70
7. Documentation of audiogram review and follow- up actions:
• review of each audiogram by professional or technician
• credentials of audiologist or physician reviewer
• reviewer’s follow- up recommendations
• documentation that the employer did recommended follow- up
• documentation of employee��s written notification of STS
• employee’s signature indicating OSHA STS follow- up
• documentation of HPD utilization enforcement after STS
B. Additional Records Employer Should Keep for the HCP
1. Audiometric Phase:
• auditory history information for each employee in HCP
• annual history updates
• annual otoscopic checks
• pre- employment or pre- exposure audiograms
• termination audiograms
2. Hearing Protection Phase:
• dates of HPD reissuing, brand and size reissued
• annual documentation at audiogram time that:
• employee’s HPD is correct size, in good condition
• employee can demonstrate proper use of the HPD
• list of HPDs the employer allows to be used in work environ-ments
with different TWA ranges, considering real- world atten-uation
( must derate the NRR)
3. Sound Exposure Monitoring:
• noise map of the facility, showing:
• areas where HPDs are optional
[ TWAs below 90 dB( A)]
• HPD- required areas
[ TWAs = 90 dB( A) or higher]
• areas where only certain HPDs are acceptable
[ TWAs = 95 dB( A) or higher]
guidelines have been met. For instance, has the key
individual made a point to get feedback from the HDP
reissuers and employees concerning the practicality of
the new earplug?
The checklist approach is fine as far as it goes, but it
does not assess the effectiveness of the program, just its
completeness. To evaluate whether hearing loss is really
being prevented, a different approach is needed.
Audiometric Data Base Analysis ( ADBA)
The audiometric results for the noise- exposed
employees provide the only objective indication of
whether the HCP is succeeding in preventing occupa-tional
hearing loss. Reviewing the audiometric records
for employees one at a time detects hearing changes for
individuals, but it does not provide an overall picture of
how well the group of workers is being protected. In
contrast, analysis of group audiometric data can show
the trends for departments and the whole plant.
Over the past several years, the ANSI S12- 12
Working Group for Evaluation of Hearing Conservation
Programs ( see Resources, item 5) has been developing
simple procedures that the employer can apply to the
audiometric data for a group of exposed employees to
assess whether they are being adequately protected.
The advantage of audiometric data base analysis
( ADBA) procedures is that problems in the HCP can be
detected early, before individual workers develop signif-icant
permanent hearing loss. If the results show that
the HCP is ineffective, the employer can improve pro-gram
practices to prevent additional hearing loss from
developing.
71
Audiograms do not prevent hearing
loss but using ADBA results can!
The ANSI S12- 12 Working Group has recently issued
its recommendations for procedures to use in evaluating
the effectiveness of HCPs. The general guidelines and
two of the recommended ADBA procedures are summa-rized
below, and detailed discussions are available. See
References, items 18– 20.
Audiometric Variability as an Indicator
The procedures recommended for audiometric data
base analysis are based on the year- to- year variability
in audiometric thresholds. If you look at the audiogram
results for a person from one year to the next, thresh-olds
at some frequencies may be a little better while
thresholds at other frequencies may be a bit worse.
Variability in audiometric threshold measurements
comes from three main sources:
1. Normal fluctuations in the responsiveness of the
person being tested ( unavoidable variability)
2. Inconsistencies in the equipment and testing
methods used to administer the audiogram ( avoid-able
measurement error)
3. True threshold changes due to temporary or perma-nent
hearing loss if employees receive inadequate
protection from noise ( what the HCP is trying to
prevent)
ADBA looks at the total variability in employees’
hearing threshold measurements. If the variability in
the HCP is in the same low range that is achieved in
low- noise- exposed or nonexposed industrial groups, then
the HCP is judged to be successful in avoiding measure-ment
error and in preventing hearing loss. However, if
variability is too high, then the hearing conservationist
must determine whether the cause is a problem with the
audiometric testing procedures or a real indication of
developing hearing loss resulting from inadequate pro-tection.
Until the variability is reduced, the HCP is
judged ineffective, because unreliable audiometric
72
results may not be capable of identifying actual hearing
loss in individuals.
Recommended Guidelines
Two variability procedures recommended by the
ANSI S12- 12 Working Group are based on counting the
percentage of employees whose hearing shows changes
of 15 dB or more between two sequential ( consecutive)
annual audiograms, such as from test 1 to test 2, or
from test 2 to test 3. Threshold changes are counted
both toward better hearing and toward worse hearing to
yield values for these two ADBA procedures:
1. Percent Worse Sequential (% Ws): the percentage
of employees who show a worsening of 15 dB or
more in thresholds for at least one test frequency
( 500 Hz through 6,000 Hz) in either ear between
two sequential audiograms
2. Percent Better or Worse Sequential (% BWs): the
percentage of employees who show either an
improvement or a worsening of 15 dB or more in
thresholds for at least one test frequency ( 500 Hz
through 6,000 Hz) in either ear between two
sequential audiograms.
Based on applying these procedures to the audio-metric
data for over 20 industrial HCPs, the ANSI
S12- 12 Working Group has defined ranges of val-ues
that indicate the HCP’s quality as acceptable,
marginal, or unacceptable. These ranges are
shown in table 5. The ranges are slightly different
for the first four years of audiometric testing
( sequential test comparisons 1– 2, 2– 3, and 3– 4)
than for later years of testing. Note that before the
procedures are applied, the population must be
restricted to a group of workers who all have the
same number of audiograms ( ideally, six or more).
73
Table 5
Criterion Ranges for Rating HCP Effectiveness by
Using ADBA Procedures Recommended by the ANSI
S12- 12 Working Group for Evaluation Hearing
Conservation Programs
Advantages and Benefits of ADBA
By using the variability procedures to evaluate the
audiometric data, HCP personnel can detect problems
in the HCP quickly— within one or two years— then act
to correct the deficiencies before many employees devel-op
significant permanent hearing changes. In other
words, the analysis helps HCP personnel to prevent
hearing loss, as illustrated in figure 2.
Simple bar graphs of ADBA results provide useful
feedback for the supervisors and employees in different
departments to show how better HPD utilization pro-duces
lower variability ( see References, item 18). These
concrete results can be effective in motivating employ-ees.
The key individual can use ADBA procedures to
guide policy decisions. If HCP personnel are unsure
whether a particular HPD provides adequate protec-tion,
the ADBA results for employees wearing different
HPDs can be compared. Similar department compar-isons
can show whether required HPD utilization is
74
Recommended percentage values for the % Ws and % BWs ADBA
Procedures ( Sequential Test Comparisons and No Age Corrections)
HCP Rating Over First Four Over Later Test Comparisons
Test Comparisons ( 5– 6, 6– 7, 7– 8, etc.)
( 1– 1, 2– 3, and 3– 4)
% Ws % Ws % Bws
Acceptable < 20 < 17 < 26
Marginal 20 to 30 17 to 27 26 to 40
Unacceptable > 30 > 27 > 40
needed to protect employees in a low- noise department
( see References, item 20).
Figure 2
Using ADBA
Finally, ADBA findings give objective evidence to
demonstrate for management when the budget alloca-tions
for the HCP need to be increased or redistributed
in order to improve protection in departments with
poorer performance. After HCP changes have been
implemented, ADBA results show management the
associated gains, less hearing loss and reduced poten-tial
liability for workers’ compensation claims.
75
➪
{ Noise Environment }
➪
➪
➪
Hearing Loss Begins ADBA Flags HCP STS Confirmed
Service
When the company uses audiometric data base analysis ( ADBA),
problems in the HCP can be detected before employees develop
significant permanent hearing threshold shifts.
Checklist for HCP Evaluation
There is a key individual overseeing all five phas-es
of the HCP.
HCP team members check that all tasks are
accomplished and documented.
HPDs are potentially effective in actual use.
HPD utilization is enforced.
Active communication is maintained among HCP
team members and all personnel up and down the
company hierarchy.
Management holds personnel accountable for their
HCP performance and gives praise or criticism as
appropriate.
Audiometric data base analysis is used to evaluate
the HCP’s effectiveness in preventing on- the- job
hearing loss.
76
References
1. Royster, L. H., Royster, J. D., and Berger, E. H.
Guidelines for developing an effective hearing con-servation
program. Sound and Vibration, volume
16( 5), pages 22– 25, 1982.
2. Royster, L. H., and Royster, J. D. An Overview of
Effective Hearing Conservation Programs. Sound
and Vibration, volume 19( 2), pages 20– 23, 1985.
3. Royster, L. H., and Royster, J. D. Education and
Motivation. In E. H. Berger, W. D. Ward, J. C.
Morrill, and L. H. Royster ( Editors), Noise and
Hearing Conservation Manual, fourth edition.
Akron, Ohio: American Industrial Hygiene
Association, 1986.
4. Berger, E. H., Royster, J. D., Royster, L. H., and
Brus, D. An Earful of Sound Advice about Hearing
Protection. Indianapolis, Indiana: E- A- R Division
of Cabot Corporation, 1988.
5. Royster, L. H., Berger, E. H., and Royster, J. D.
Noise Surveys and Data Analysis. In E. H. Berger,
W. D. Ward, J. C. Morrill, and L. H. Royster
( Editors), Noise and Hearing Conservation
Manual, fourth edition. Akron, Ohio: American
Industrial Hygiene Association, 1986.
6. Bruce, R. D., and Toothman, E. H. Engineering
Controls. In E. H. Berger, W. D. Ward, J. C.
Morrill, and L. H. Royster ( Editors), Noise and
Hearing Conservation Manual, fourth edition.
Akron, Ohio: American Industrial Hygiene
Association, 1986.
7. Purcell, W. E. Materials for Noise and Vibration
Control. Sound and Vibration, volume 14( 7), pages
8– 32, 1980.
77
8. Purcell, W. E. Systems for Noise and Vibration
Control. Sound and Vibration, volume 14( 8), pages
10– 36, 1980.
9. Irwin, J. D., and Graf, E. R. Industrial Noise and
Vibration Control. Englewood Cliffs, New Jersey:
Prentice- Hall, 1979.
10. Wilson, Charles E. Noise Control: Measurement,
Analysis, and Control of Sound and Vibration.
New York: Harper and Row Publisher

Click tabs to swap between content that is broken into logical sections.

A Guide to
Developing and Maintaining
an Effective Hearing
Conservation Program
Julia and Larry Royster
Sydney Cheryl Sutton
Editor
N. C. Department of Labor
Division of Occupational Safety and Health
1101 Mail Service Center
Raleigh, NC 27699- 1101
Cherie K. Berry
Commissioner of Labor
Acknowledgments
This industry guide was prepared for the North Carolina Department of Labor by Julia
and Larry Royster. Julia Doswell Royster, Ph. D., CCC- A/ SLP, is President of
Environmental Noise Consultants, Inc., of Raleigh, North Carolina ( email:
effective_ hcps@ compuserve. com). Larry H. Royster, Ph. D., is a professor in the
Department of Mechanical and Aerospace Engineering, North Carolina State
University, Raleigh, North Carolina. Mr. Royster wrote the original North Carolina
OSHA noise guidelines and Noise Compliance Plan. Numerous publications have
reported the research of both authors ( see References in this publication). Each author
is recognized as an expert in the areas of noise control and hearing conservation.
Most of the illustrations for this publication were prepared by the E- A- R Division of
Aearo Company. The Aearo Company has granted permission for the use of the illus-trations
in this industry guide.
This guide is intended to be consistent with all existing OSHA standards; there-fore,
if an area is considered by the reader to be inconsistent with a standard,
then the OSHA standard should be followed.
To obtain additional copies of this book, or if you have ques-tions
about N. C. occupational safety and health standards
or rules, please contact:
N. C. Department of Labor
Bureau of Education, Training and Technical Assistance
1101 Mail Service Center
Raleigh, NC 27699- 1101
Phone: ( 919) 807- 2875 or 1- 800- NC- LABOR
____________________
Additional sources of information are listed
on the inside back cover of this book.
____________________
The projected cost of the OSHNC program for federal fiscal year 2002– 2003 is $ 13,130,589.
Federal funding provides approximately 37 percent ($ 4,920,000) of this total.
Printed 7/ 98, 3M
N. C. Department of Labor
Occupational Safety and Health Program
Cherie K. Berry
Commissioner of Labor
OSHA State Plan Designee
Allen McNeely
Deputy Commissioner for Safety and Health
Kevin Beauregard
Assistant Deputy Commissioner for Safety and Health
Contents
Part Page
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1ivi
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1vii
1 Effective Hearing Conservation Programs
( HCPs): Benefits and Strategies . . . . . . . . . . iiv1
A Look at HCPs Nationwide . . . . . . . . . . . . . iiv1
Benefits of the HCP to the Employee . . . iiv3
Benefits of the HCP to the Employer . . . iiv3
2 Organizing Your HCP: Five Phases under
a Key Individual . . . . . . . . . . . . . . . . . . . . . . . . . . . . iiv5
Five Related Phases . . . . . . . . . . . . . . . . . . . . . . iiv5
Characteristics of Effective HCPs . . . . . . . iiv9
Personnel Involved in the HCP . . . . . . . . . . ii10
External Influences on the HCP . . . . . . . . . ii11
Organization Makes the Difference . . . . . ii12
Checklist for HCP Development . . . . . . . . . ii12
3 Education and Motivation. . . . . . . . . . . . . . . . . . . ii13
Education Paves the Way for
Other Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii13
Making Education a Priority. . . . . . . . . . . . . ii14
Developing Adequate Personnel
Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii14
Organizing Sessions for Best Results . . . ii14
A Relevant Approach to Education. . . . . . ii15
Tailoring the Presentation to the
Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii18
Taking Advantage of Motivational
Opportunities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii19
Questions and Suggestions. . . . . . . . . . . . . . . ii19
Checklist for Education and
Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii20
iii
4 Sound Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii21
Types of Surveys and
Instrumentation. . . . . . . . . . . . . . . . . . . . . . . . . . ii21
Ways Sound Survey Results Are Used . . . ii22
Keeping Surveys in Perspective . . . . . . . . . ii22
Planning and Coordinating with
Production Personnel . . . . . . . . . . . . . . . . . . . . ii23
Data Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii24
Employee Participation Is Essential . . . . ii25
Report Preparation. . . . . . . . . . . . . . . . . . . . . . . . ii26
Communicating Exposure Results . . . . . . ii27
Checklist for Sound Surveys . . . . . . . . . . . . . ii27
5 Engineering and Administrative Noise
Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii28
Engineering Controls . . . . . . . . . . . . . . . . . . . . . ii28
Administrative Controls . . . . . . . . . . . . . . . . . . ii33
Solving Noise Control Problems
Using In- House Personnel . . . . . . . . . . . . . . ii36
Sources of Information. . . . . . . . . . . . . . . . . . . . ii37
Checklist for Noise Controls . . . . . . . . . . . . . ii38
6 Hearing Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . ii39
Organizing the HPD Phase for
Success . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii39
Types of HPDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii40
Hearing Protector Attenuation . . . . . . . . . . ii41
Real- World Attenuation . . . . . . . . . . . . . . . . . . ii43
Purchasing Appropriate HPDs . . . . . . . . . . ii44
Maximizing the Effectiveness of HPDs
in Actual Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii47
Motivating Employees to Wear HPDs
Effectively. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii49
Demonstrating Management Support . . ii50
Checklist for Hearing Protection . . . . . . . . ii52
iv
7 Audiometric Evaluations . . . . . . . . . . . . . . . . . . . . ii53
Management Support Needed for
Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii53
Quality Control Responsibilities of
Audiometric Technicians . . . . . . . . . . . . . . . . ii58
Scheduling Audiograms . . . . . . . . . . . . . . . . . . ii60
Using the Audiogram Session to Best
Advantage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii61
Following up on Audiometric Results . . . ii62
Educating Employees to Take
Responsibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii65
Checklist for Audiometric Evaluations. . . ii65
8 Making Sure That the HCP Works. . . . . . . . . ii67
The Team Approach . . . . . . . . . . . . . . . . . . . . . . . ii67
Documentation and Recordkeeping . . . . . ii67
Recording Hearing Loss on the OSHA
200 Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii68
Assessing Your HCP. . . . . . . . . . . . . . . . . . . . . . . ii70
Audiometric Data Base Analysis
( ADBA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii71
Checklist for HCP Evaluation . . . . . . . . . . . ii76
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii77
Resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii80
v
Foreword
The ear is a delicate organ. Serious damage to the
ears can leave a person partially or completely deaf.
Sudden extreme loud noise or prolonged loud noise may
cause permanent injury to the hearing. Workers in very
noisy industries may be affected over time if hearing
protection programs are not initiated and followed.
Employers must be aware of workplace hazards facing
their employees and take appropriate action to minimize
or eliminate exposure to these hazards. A Guide to
Developing and Maintaining an Effective Hearing
Conservation Program describes a program that
employers can implement to protect their employees’
hearing ability.
In this state, the North Carolina Department of Labor
consultants and inspectors administer the federal OSHA
laws through a plan approved by the U. S. Department of
Labor. All current OSHA standards are enforced. Many
educational programs, publications ( including this
guide), and other services are also offered to help inform
people about their rights and responsibilities regarding
OSHA.
As you look through this guide, please remember that
OSHA’s mission is greater than just enforcement. An
equally important goal is to help citizens find ways to
create safe and healthy workplaces. Reading and using
the information in this booklet, like other educational
materials produced by the North Carolina Department
of Labor, can help.
Cherie K. Berry
Commissioner of Labor
vi
Introduction
This publication describes a program that employers
can implement to protect their employees’ hearing abili-ty.
The writers intended to take the reader beyond the
minimum provisions of OSHA requirements. They did
not intend to create a guide to the OSHA occupational
noise exposure standard. If at any point the OSHA stan-dard
and information here should appear to conflict, the
standard must be considered controlling. Therefore, the
reader should be acquainted with the OSHA standard.
The occupational noise exposure standard is included
in the North Carolina OSHA Standards for General
Industry. Contact the Standards, Analysis, and
Publications Section, Division of Occupational Safety
and Health, North Carolina Department of Labor, for a
copy of the standards and for assistance in interpreting
them. ( See the inside back cover of this publication for
the address and telephone number.)
The occupational noise exposure standard is at 29
CFR 1910.95. Parts of the standard that provide particu-larly
helpful background for reading this guide include:
Sections .95( c)–( oo)— inform of the circumstances
under which the employer must implement a hearing
conservation program ( HCP) and describe the elements
of an acceptable HCP
Section .95( b)( l)— requires the use of feasible adminis-trative
and engineering controls
Section .95( f)— provides that employees must be pro-vided
an opportunity to observe noise measurements as
they are conducted
Section .95( l)— describes types of information ( includ-ing
copies of the standard) that must be posted in the
workplace and/ or otherwise made available to employees
vii
Section .95( i)— requires employers that are required
to establish an HCP:
• provide hearing protectors at no cost to employees
• allow employees to select from a variety of hearing
protectors
• ensure the proper initial fit of hearing protectors
• train employees in the use and care of the hearing
protectors that they select for their use
• ensure that employees wear their hearing protec-tors
viii
1
Effective Hearing
Conservation Programs ( HCPs):
Benefits and Strategies
The purpose of industrial hearing conservation pro-grams
( HCPS) is to prevent employees from developing
noise- induced hearing loss on the job. After occupational
hearing loss was recognized as a health problem, the
Occupational Safety and Health Administration ( OSHA)
promulgated regulations that specified minimum
requirements for employers to meet. However, simply
complying with the OSHA regulations does not guaran-tee
that a program will be effective in preventing occu-pational
hearing loss, as many unsuccessful HCPs
demonstrate.
If the employer runs an ineffective HCP, there is no
payback for the time and resources invested. An ineffec-tive
HCP is only an exercise in regulatory compliance.
However, the goal of preventing occupational hearing
loss can be achieved if the employer applies a few basic
principles in organizing the HCP. Our experience with
industries across the country indicates that there is no
correlation between the amount of money spent on the
HCP and its effectiveness. However, if management
ensures that the HCP has the desired characteristics
described in this guide, the program will succeed.
A Look at HCPs Nationwide
During 1980– 84 the authors of this publication
received a grant through N. C. State University from the
E- A- R Division of Cabot Corporation to conduct on- site
interviews with HCP personnel nationwide to describe
1
the use of hearing protection devices ( HPDs) in 218
industries of all types. In addition to the structured
questionnaire results about HPDs, comments from
those interviewed and observations provided insights
about common mistakes in HCP implementation and
organization. Some frequent causes of HCP ineffective-ness
are shown in table 1.
Table 1
Frequent Causes of HCP Ineffectiveness
By avoiding pitfalls such as those shown in table 1
and by following the tips in this booklet, the employer
can develop an effective HCP. The policies and proce-dures
outlined in this publication have proved useful in
HCPs in a variety of industries around the United
States and will probably apply to most production facili-ties.
Nevertheless, because it is impossible to specify
2
• Inadequate communication and coordination among: ( 1) plant
personnel involved in the HCP and ( 2) on- site personnel and
corporate headquarters
• Insufficient or erroneous information used to make HCP
decisions
• No meaningful training for HPD fitters and reissuers
• Inadequate or inappropriate selection of HPDs in stock and
over- reliance on noise reduction ratings in choosing HPDs
• Failure to fit and train each HPD wearer individually
• Over- reliance on contractors to provide HCP services
• Failure to use the audiometric monitoring results to educate
and motivate employees
• Failure to use audiometric data to evaluate the effectiveness
of the HCP
HCP guidelines to cover every situation, the hearing
conservationist has to use common sense in evaluating
whether particular pieces of advice are workable for
each plant’s HCP. Local personnel can judge best how to
tailor the guidelines for their facility in order to achieve
the goal: prevention of occupational hearing loss.
Benefits of the HCP to the Employee
Preventing hearing loss on the job is the primary
employee benefit of the HCP, but just why is this impor-tant?
Hearing loss from any cause reduces the quality
of life for the affected individual. Hearing impairment
interferes with normal communication, and communica-tion
is a significant part of life. For many jobs we need
adequate hearing to qualify to be hired or promoted, so
hearing loss decreases our employment potential. On
the job we need good communication ability to give and
receive instructions, use the telephone, and detect
machinery sounds and warning signals. Off the job our
interpersonal communication with family and friends
puts pleasure in our lives and gives us a feeling of being
involved with others in recreational situations and at
home. We also need our hearing to enjoy music and the
quiet sounds of nature. For all of those reasons and
more, good hearing is invaluable.
The HCP also provides a health screening benefit for
employees, since nonoccupational hearing losses and
potentially treatable ear diseases are often detected
through the annual audiograms.
Benefits of the HCP to the Employer
The employer benefits directly by implementing an
effective HCP that maintains employees’ good hearing,
since workers will remain more productive if their com-munication
abilities are not impaired. Employees with
good hearing are also more versatile and can be promoted
3
to jobs where communication ( especially by telephone) is
even more important. Effective HCPs can reduce accident
rates and promote work efficiency, as well as reduce the
stress and fatigue related to noise exposure.
The HCP is one aspect of the employer’s overall poli-cy
toward worker health and safety practices, and
employee relations are better and job turnover is lower
for companies that pay attention to the working envi-ronment.
Maintaining a safe and healthy workplace
contributes to the company’s prestige and image as a
desirable employer.
An effective HCP also lessens monetary losses from
workers’ compensation claims and insurance premiums.
Further, the effective HCP is cost- effective in that while
compliance with OSHA and other governmental regula-tions
is achieved, loss prevention and productivity gains
are also realized.
4
2
Organizing Your HCP:
Five Phases under a Key
Individual
Figure 1 presents an outline of the major aspects of a
HCP. The five phases of the program are shown in the
first column. The second column lists characteristics
that differentiate effective HCPs from unsuccessful pro-grams.
The third column indicates various company per-sonnel
who are important to HCP success. The fourth
column lists influences external to the company that
may also affect the HCP. Each of these aspects is dis-cussed
below, and additional information is available.
( See References, items 1 and 2.)
Five Related Phases
The phases of every HCP are education, sound expo-sure
surveys, engineering and/ or administrative noise
controls, hearing protection, and audiometric evalua-tions.
The relative emphasis placed on the phases may
vary according to the needs of the particular production
facility, but each one is essential for an effective program.
The Education Phase
The education phase is the most important because
HCP personnel and employees will not actively partici-pate
in hearing conservation unless they understand its
purpose and how they will benefit directly from the pro-gram,
and know that compliance with the company’s
safety and health requirements is a condition of employ-ment.
Without meaningful education to motivate indi-vidual
actions, the HCP will fail. Educational efforts
must begin even before sound surveys and engineering
5
6
Hearing Conservation Program
Five
Phases
Desired
Characteristics
Personnel
Involved
External
Influences
Company
Headquarters
Top
Management
Enforcement of
Hearing Protec-tion
Utilization
Engineering
Administrative
Controls
Middle
Management
Key
Hearing Individual
Protection
Audiometric
Monitoring
Active
Communications
Education Top Manager
Sound Surveys
Consultants
Suppliers
Second Job
Community
Supervisors
Employees
Leisure Time
Hobbies, etc.
Potentially
Effective
Hearing Pro-tection
Devices
Figure 1
Hearing Conservation Program ( HCP) Phases,
Desired Characteristics, Personnel Involved, and
External Influences That Affect HCP Function
controls are carried out in order to obtain representative
exposure results and to develop employee acceptance of
machine modifications. Likewise, the success of the
hearing protection and audiometric phases depends on
teaching employees how to understand and take care of
their hearing. In effective HCPs the educational phase is
continuous— not just an annual presentation— as HCP
personnel take daily opportunities to remind others
about conserving their hearing.
The Sound Survey Phase
The sound survey phase involves determining the
degree of hazardous noise exposure for workers so that
appropriate HCP policies can be established to protect
them. For example, the choices of hearing protectors
available to employees may be limited to the most
effective devices for departments with very high noise
exposures. In addition, sound surveys can identify the
dominant noise sources in each area of the plant and
determine where engineering controls can significantly
reduce employee exposures.
The Engineering and Administrative
Noise Controls Phase
The engineering and administrative noise controls
phase attempts to reduce employees’ noise exposures to
nonhazardous levels. Engineering controls involve modi-fication
of the noise source ( such as by fitting mufflers to
air exhaust nozzles), the noise path ( such as by placing
sound- absorbent enclosures around equipment), or the
receiver ( such as by constructing an enclosure around
the employee’s work station). Administrative noise con-trols
include changes in employees’ work schedules or
task assignments to reduce noise exposures by limiting
exposure time. The ultimate goal is to eliminate employ-ee
exposures to harmful noise. However, significant
reductions in exposure are very important because it is
much easier to achieve effective protection for employees
7
using hearing protection devices if the exposures are
lower rather than higher. Application of retrofit noise
controls to existing machinery may be effective. But
when the employer purchases new equipment, an excel-lent
opportunity exists to demand reduced sound level
output as part of the specifications required of the equip-ment
manufacturer. In addition, regular maintenance
programs for equipment and for its noise control modifi-cations
help keep noise levels down as well as extend the
life of the machinery.
The Hearing Protection Phase
The hearing protection phase of the HCP provides
hearing protection devices ( HPDs) for employees and
training in how to wear them as long as hazardous
noise levels exist in the workplace. Because feasible
engineering noise controls have not been developed for
many types of industrial equipment, HPDs are the best
current option for preventing noise- induced hearing loss
in these situations.
The Audiometric Evaluations Phase
The audiometric evaluations phase of the HCP ties
together the whole program. Each exposed employee
receives an annual hearing cheek to monitor hearing
status and detect any hearing change. If the HCP is
working, employees’ audiometric results will not show
changes associated with on- the- job noise- induced hear-ing
damage. If suspicious hearing changes are found,
the audiometric technician and the audiologist who
reviews the record can counsel the employee to wear
HPDs more carefully, assess whether more effective
HPDs are needed, and motivate the individual to be
more careful in protecting his or her hearing both on
and off the job. Sometimes nonoccupational causes of
hearing change may be identified, such as gunfire or
hobby noise exposure or medical ear problems.
8
Characteristics of Effective HCPs
HPDs— Effective and Enforced
The importance of HPD policies to HCP success is
underscored by the first two desired characteristics of
effective HCPS: strict enforcement of HPD utilization
( actual enforcement, not just a paper policy) and the
availability of HPDs that are potentially effective for the
work environment. Potentially effective HPDs are
devices that are practical and comfortable enough for
employees to wear them consistently and provide ade-quate
sound attenuation.
The Key Individual
The most important strategy for making the five
phases of the HCP function together effectively is to
unite them under the supervision of one key individual.
In smaller companies where one person may actually
carry out all facets of the HCP, lack of coordination is
not usually a problem. However, as company size
increases, different types of staff become involved in the
HCP: safety personnel, medical personnel, engineers,
industrial hygienists, tool crib supervisors, and produc-tion
supervisors. With personnel from varying disci-plines
carrying out different aspects of the program, it
becomes very difficult to coordinate their efforts unless
one key individual is overseeing the entire HCP. The
choice of who this person should be is critical to the suc-cess
of the program. The primary qualification for the
key individual is genuine interest in the company’s HCP.
Nonetheless, selecting the key individual does not mini-mize
the crucial importance of the line supervisor to the
success of the HCP.
Since extra training is easy to obtain through brief
courses such as those approved by the Council for
Accreditation in Occupational Hearing Conservation
( CAOHC) ( see Resources, item 2), the background of
the key individual is less important than his or her
9
enthusiasm and ability to relate to people. The key
individuals we have observed know everyone by name
and are equally friendly with production employees
and managers. The key individual is approachable and
is always sincerely interested in comments or com-plaints
that can help to improve the HCP. This individ-ual
does not stay in an office, running the HCP on
paper by mandate, but spends time on the production
floors to interact with employees and observe how prob-lems
can be prevented or solved.
Active Communications
The key individual maintains communication among
all company personnel involved in the HCP by passing
information both up and down the hierarchy. The pri-mary
HCP team members meet together regularly to
update each other on the progress of the program. Once
people with different tasks understand how their own
parts contribute to the overall outcome of the program,
they will respond to feedback about their performance
by cooperating to prevent hearing loss. The key individ-ual
can achieve this active communication and coopera-tion
if management provides him or her with the
authority to make HCP decisions and the resource
allocations to act on decisions once they are made.
Personnel Involved in the HCP
The success of the HCP depends on everyone from the
top manager to the most recently hired trainee; each has
an important role. For management, the role is largely to
support the HCP and enforce its policies as one facet of
the company’s overall health and safety program. For
middle management and supervisors, the role is more
direct: these staff members are part of the primary HCP
team, which carries out the five phases. Their duties
include monitoring noise exposures, maintaining engi-neering
controls, participating in educational efforts, fit-ting
HPDs and reissuing HPD replacements, supervising
10
daily HPD utilization, performing the audiometric evalu-ations,
and giving feedback to employees about their
hearing results. The role of employees is to participate
actively in the program and to make suggestions as to
how to improve HCP operation. However, for employee
participation to succeed, the HCP team must be receptive
to comments and respond to employee input.
External Influences on the HCP
If local HCP decisions are limited by policies mandat-ed
by corporate headquarters, the key individual may
need top management’s assistance in obtaining excep-tions
to the corporate rules in order to meet local needs.
The key individual also must keep control over any ser-vices
provided by outside contractors ( such as sound
surveys or audiograms). When contractors are used, it
is more difficult to integrate their services cohesively
into the overall HCP, but it is critical to do so. If in-plant
personnel do not follow through by using the
information provided by the contractors, then the con-tracted
elements of the program lose effectiveness.
Finally, employees’ hearing is affected by off- the- job
activities such as recreational target shooting or use of
power tools in farming or woodworking. The HCP can-not
save workers’ hearing through protection on the job
unless employees are educated to protect their ears dur-ing
off- the- job noise exposures. The wise employer
encourages employees to take HPDs home for use in
nonoccupational noisy situations. Meaningful educa-tional
programs focus on the importance of good hear-ing
for enjoyment of social and recreational activities, so
the employee will appreciate the employer’s concern for
hearing conservation in all parts of life.
11
Organization Makes the Difference
Most HCPs make at least some efforts in each of the
five phases, but most programs remain ineffective
because they are fragmented and incomplete. When
HCP personnel lack adequate training to carry out their
duties, have no direct supervision to coordinate their
efforts, and are not evaluated on their performance, the
HCP fails. By putting an interested and capable person
in charge of all five phases, then authorizing this key
individual to make decisions and take actions to
improve the program, management will be rewarded by
a cost- effective, successful HCP.
Checklist for HCP Development
All five HCP phases have been implemented.
There is a key individual in charge of the HCP
team.
HPDs are potentially effective in actual use.
HPD utilization is enforced.
There is active communication among the HCP
team members and personnel at all levels.
12
3
Education and Motivation
Education and motivation are critical to helping
employees actively participate in the HCP and generat-ing
the sincere support of the program by management.
Regular educational and motivational activities related
to hearing conservation develop interest in the program
and keep the importance of the HCP in mind through-out
the year. Any HCP that attempts to skip over this
phase of the program will find other phases failing
because personnel do not understand why it is in their
own best interest to cooperate in the HCP and take
advantage of its benefits. For more details about educa-tion
and motivation, see References, items 3 and 4.
Education Paves the Way for Other
Phases
When sound surveys are planned to determine
whether a HCP needs to be established, limited educa-tional
efforts must come first to notify supervisors and
employees about the purpose of the sound surveys and
to explain that their assistance is important for obtain-ing
accurate sound measurements. Employees will be
much more cooperative if they are informed in advance
of what will be happening and why.
If a noise problem is identified during sound surveys,
then a more formal educational program needs to be
given before the noise control, hearing protection, and
audiometric evaluation phases of the HCP are initiated.
This start- up program would present the results of the
sound surveys, explain the risks of noise- induced hear-ing
loss, and introduce the HCP policies established for
various areas or departments of the plant.
13
Making Education a Priority
Management must emphasize the importance of the
educational phase by scheduling regular training ses-sions
and requiring attendance. Educational sessions
should be held not only for employees who are regularly
over- exposed to noise, but also for employees who occa-sionally
enter the HPD- required areas of the plant and
for the supervisors and managers responsible for pro-duction
areas with hazardous noise. When a company’s
HCP is being introduced, a manager should participate
in each educational session to outline company policies
and demonstrate the company’s commitment to the
HCP. In an established HCP, a manager should partici-pate
in educational sessions to the degree practical to
reinforce the company’s priority on the HCP.
Developing Adequate Personnel
Resources
Management must ensure that the primary HCP team
members ( the key individual, audiometric technicians,
HPD fitters and issuers, and supervisors) have received
sufficient education about hearing conservation. Then
they will be qualified and comfortable carrying out their
HCP responsibilities, as well as leading employee train-ing
sessions and answering employees’ questions. The
success of the program depends on this team.
Organizing Sessions for Best Results
The educational sessions work best in small groups con-sisting
of the presenters plus the supervisor and employees
in a production unit. These individuals will typically have
common noise exposures, will fall under a common HPD
policy, and will feel comfortable enough with each other to
ask questions freely. Management must also ensure that
employee questions and concerns raised during educational
sessions receive thoughtful and prompt follow- up. Separate
14
sessions should be held for supervisors of noisy depart-ments
and their managers, so that they can discuss com-pany
policy concerns prior to meeting with employees.
These groups need more detailed information to prepare
for questions employees may later ask during educational
sessions or when back in their departments.
A Relevant Approach to Education
To hold employees’ interest, the personnel who make
the main presentations in formal educational programs
must be selected to project genuine interest in employees’
welfare, and the program content must be updated every
year.
Keep it:
• Short
• Simple
• Meaningful
• Motivating
The annual educational program covers practical aspects of all five
phases of the company‘ s HCP and gives employees a chance to ask
questions.
15
Educators should limit the content to a brief, simple
presentation of the most relevant facts for employees.
The focus should be on the real- life reasons of why it is
to the advantage of employees to protect their hearing
in order to maintain their quality of life: to preserve
speech understanding ability in both work settings and
social environments, to enjoy music, and to perceive
auditory warnings and signals such as car engine noises
that indicate malfunctions.
Information to help employees understand how their
audiogram results compare to expected age- effect hear-ing
loss will increase the motivational benefit of the
audiometric phase. Once employees are familiar with
their audiogram results and know the reasons why they
need to preserve their hearing, the remainder of the
program can focus on how to protect their hearing on
and off the job. Employees protect themselves by the
effective use of HPDs and engineering noise controls,
plus administrative controls including good general
maintenance of production equipment. The educational
program should stress how the HCP benefits employees
by protecting their hearing at work and detecting hear-ing
changes that result from medical conditions and
nonoccupational noise exposures. A sample educational
outline is shown as table 2.
16
17
Table 2
Suggested Educational Program Content
How noise damages our hearing
Consequences of hearing loss in everyday life
Diminished ability to understand speech
Social isolation from friends and family
Interference with work and leisure activities
Noise exposures that are hazardous
Off the job ( gunfire; power tools)
On the job ( sound survey results for plant)
Engineering and/ or administrative noise controls imple-mented
or planned
HPD choices for the employees’ department
Using them correctly
Caring for and replacing them
Solving common HPD problems or complaints
Audiometric evaluations— purpose and procedures
Understand your own audiogram results
Hearing changes may mean inadequate protection
Nonoccupational hearing loss may be detected
Ways to protect your hearing on and off the job
Wear HPDs correctly and consistently
Avoid unnecessary noise exposures
Use engineering and administrative noise controls
The company’s HCP policies
The importance of the HCP to management
HCP participation as a condition of employment
Questions and answers
Final motivation
The HCP as a benefit for employees
Participation is to employees’ own advantage
Tailoring the Presentation to the
Audience
Presenters need to make the educational program’s
content specific to the particular group of employees
attending with their supervisor. Presenters should
mention the employees’ specific noise exposures, the HPD
options available, and the engineering controls in place or
planned for their department. For the separate sessions
for supervisors and managers, greater details and differ-ent
emphases are appropriate to address the concerns of
these personnel. Such sessions may present a progress
report on the status of the HCP, review of the company’s
legal obligations for regulatory compliance, comparisons
of audiometric and HPD utilization indicators by depart-ment,
and answers for questions that employees may ask.
Films and pamphlets should be used only as supplemen-tary
reinforcements for live presentations, never as the
whole program. Verbal presentations and audiovisual
aids should be changed annually.
People with noise- induced hearing loss usually find it hard to understand
the high- pitched voices of children and women. By protecting your hear-ing,
you can prevent noise damage from affecting your family life.
18
Taking Advantage of Motivational
Opportunities
Aside from formal educational presentations, HCP
personnel should use every chance to remind employees
and supervisors of the importance of the HCP and their
active participation in it, especially concerning hearing
protection. The greatest opportunity to influence
employees occurs at audiogram time, when the current
hearing results can be compared to past results and the
fit and condition of HPDs can be checked. Praise for
employees with stable hearing and cautions for those
with threshold shifts can be effective if the comments
come from a sincere individual. The personnel who real-ly
make HCPs come alive do not wait for this once- a-year
chance to interact with employees. They tour the
plant floor making comments and talking to workers in
the halls and cafeteria. HCP personnel need to empha-size
hearing conservation as an ongoing effort. This can
be achieved through safety meetings, rewards for
departments with excellent HCP performance, bulletin
board posters, articles in the company paper, and daily
interactions with employees. The goal is to emphasize
the HCP continually as part of the company climate.
Questions and Suggestions
Employees need time during educational sessions,
safety meetings, and their daily work to voice their con-cerns
or questions. They need the opportunity to inform
HCP personnel when certain HPDs or engineering con-trols
are not practical and to suggest alternatives that
would be more workable for their departments. If HCP
personnel do not provide adequate follow- up or consid-eration,
employees need to be able and encouraged to go
up the management line until their concerns are
addressed.
19
Checklist for Education and Motivation
Team members receive education about hearing
loss and hearing conservation to understand the
goals and policies of the HCP.
HCP team members receive training in how to
carry out their functions ( especially concerning
HPD fitting and utilization).
Employees annually attend updated educational
programs that focus on why and how to protect
their own hearing on and off the job.
HCP personnel keep the program in employees’
minds through informal reminders at least quar-terly.
Management backs up the HCP by personal exam-ple
( wearing HPDs), policy enforcement, and par-ticipation
in educational programs.
Employees are evaluated on their HCP participa-tion
during the company’s annual personnel
reviews.
20
4
Sound Surveys
The noise measurement data obtained through sound
surveys is needed to determine the degree of exposure
hazard and to make decisions about how to protect
employees. Different instruments and measurement
methods may be used depending on the type of survey
being conducted.
Types of Surveys and Instrumentation
In basic sound surveys a sound level meter is used to
identify work areas that clearly do not have a noise
problem and areas that do have potentially hazardous
noise environments. The basic survey determines the
departments where employees may need to be included
in the HCP due to their daily noise exposures ( a combi-nation
of the noise levels with their corresponding dura-tions).
In detailed sound surveys, a sound level meter
and stopwatch and/ or a personal noise dosimeter are
used to estimate the worker’s daily noise dose and
equivalent OSHA time- weighted average ( TWA) noise
exposure. In engineering sound surveys instruments
such as sound level meters, octave- band analyzers, and
recorders may be used to measure the noise levels pro-duced
by machinery in various modes of operation in
order to assess the potential for applying engineering
controls.
Surveys should be conducted on a recurrent basis:
annually, or more often if it is suspected that the
employees’ TWAs may have changed significantly. Thus,
it is often cost- effective to purchase the instrumentation
and have an on- site staff member trained to perform
sound level and exposure measurements. With in- house
expertise, the company can check sound levels whenever
21
production machinery is changed without bringing in an
external consultant. In addition, company personnel can
evaluate simple noise control options without having to
hire a consultant.
Ways Sound Survey Results Are Used
The results of sound surveys are needed for many
reasons:
• To designate those areas of the plant where haz-ardous
noise levels exist
• To identify the employees to be included in the
HCP
• To classify employee noise exposures in order to
define HPD policies and rank areas for noise con-trol
efforts
• To determine whether noise levels present a safety
hazard in terms of interference with speech com-munication
and warning signal detection
• To evaluate noise sources for noise control purposes
• To document noise levels and employee exposures
for legal purposes such as workers’ compensation
Keeping Surveys in Perspective
It is important to define the goals of the sound surveys
and limit their scope to obtaining the information needed to
guide decisions. It is not necessary to perform extremely
detailed surveys to decide how best to protect employees. In
many instances adequate data can be obtained with only a
sound level meter and a stopwatch. The time and money
devoted to exposure monitoring should be just sufficient to
make appropriate HCP decisions. The bulk of resource allo-cations
should go to the phases of the program that actually
provide protection for employees ( education, noise controls,
hearing protection, and audiometric evaluations).
22
The sound survey should result in a noise map of the
production facility. A noise map is a floor plan with
areas of the plant designated according to whether area
workers are included in the HCP and according to
which HPD utilization policy applies to the area: volun-tary
or required use, with free or restricted HPD choice.
( See table 3). Estimates of daily noise exposures for rep-resentative
employees in various jobs are also needed,
particularly for jobs in which workers are exposed to
noise that varies in level. A suggested guideline for clas-sifying
HCP policies according to the established TWAs
is shown in table 3.
Table 3
Suggested TWA Ranges for Classifying Plant Areas and
Corresponding HCP Policies for Area Employees
Planning and Coordinating with
Production Personnel
HCP personnel must plan the sound surveys to
obtain information needed to answer relevant questions
about protecting employees. If external contractors per-form
the surveys, the key individual must define the
information desired and familiarize the contractors
23
TWA, dB( A) Workers in HPD HPD Selection
the HCP Utilization Options
84 or below no voluntary free choice
85– 89 yes optional* free choice
90– 94 yes required free choice
95– 99 yes required limited choice
100 or above yes required very limited
choice
* HPD utilization will be required:
1. For any individual who shows a significant change in hearing
2. For all employees if audiometric data base analysis results
or group hearing trends indicate inadequate protection
with the environment, employee work schedules, and
production variations. Following this procedure ensures
that the desired information will be obtained.
The sound surveyor must coordinate scheduling with
production personnel to capture representative produc-tion
cycles. Supervisors can predict when noise levels will
be higher or lower, when certain pieces of equipment will
be in operation, and when downtime for repairs or main-tenance
will be scheduled. Production schedules and
machinery function do not always follow predictions.
Thus, surveyors must be flexible and return as needed to
obtain the desired data for all typical work activities. By
coordinating with supervisors to minimize interference
with production, the surveyors will enhance supervisors’
cooperation and willingness to share information.
Employee cooperation and knowledge are needed to
obtain valid survey results. Therefore, sound surveyors
must establish rapport with workers to benefit from
their familiarity with the production environment and
machinery. Experienced operators can often identify
dominant sound sources, predict time periods of relative-ly
higher or lower sound levels, and describe the effects
of different operation modes on sound levels. If survey-ors
explain the purpose of the survey to workers and
solicit their help in planning the measurements to be
made, they can avoid errors and oversights and reduce
the prospect of resentful or suspicious workers sabotag-ing
the results or damaging the instrumentation.
Data Collection
In making measurements and documenting results,
the surveyors must consistently follow accepted prac-tices
for instrument selection and calibration, measure-ment
techniques, sampling strategy, methodology
description and documentation, and data recording.
Detailed guidelines for data collection are available. ( See
References, item 5.) The American National Standards
24
Institute ( ANSI) also publishes relevant standards. ( See
Resources, item 1.) During data collection, the surveyor
must record in detail the measurement locations and
times and the procedures followed. A good rule of thumb
is to make the survey description detailed enough that
another person could follow it to replicate the results
( provided the noise environment has not changed). It is
very useful to record C- weighted as well as A- weighted
sound levels for purposes of estimating HPD adequacy
and considering engineering controls. ( For more infor-mation
about C- weighted and A- weighted sound levels,
see References, item 12.)
A noise dosimeter takes into account the variations in sound levels over
time and predicts the employee’s daily noise dose, which can be con-verted
to the TWA.
Employee Participation Is Essential
Employees can assist the sound surveyors in obtain-ing
representative results by sharing their knowledge
about the production environment, the machinery in
operation, and worker tasks. Employee assistance is
critical in operating machinery for detailed engineering
25
sound surveys intended to evaluate sound sources with-in
a unit of machinery. Employees should continue their
normal activities when wearing dosimeters for individ-ual
worker exposure monitoring to ensure that the
results will be representative.
Employees should be asked to notify HCP personnel
when the sound environment creates a possible safety
hazard due to communication difficulty or when
changes in sound levels call for a resurvey. Sound levels
may increase significantly when equipment begins to
wear, and changes in equipment placement or processes
may have unintended effects on sound levels. When
employees notice such changes, they need to inform the
sound surveyors that a resurvey is needed to evaluate
the sound levels and corresponding employee exposures.
Report Preparation
The report written after completing the sound survey
must present the results clearly. The writer should
state the survey objectives and present data relevant to
these objectives. Because few report users will need or
read the full details of the survey, it is critical to include
a concise abstract or administrative review section. A
slightly longer summary should be included for the pri-mary
HCP team.
The body of the report must summarize the calibra-tion
and measurement procedures to support the validi-ty
of the conclusions. Detailed documentation must be
kept with the report to substantiate the procedures if
they are ever questioned. Although the report will con-tain
neatly organized tables of data, the original data
recording sheets and instrument calibration sheets
should be preserved for potential legal purposes. Keep
in mind that all sound survey reports may be used as
legal documents if the company ever becomes involved
in a workers’ compensation or other suit related to the
noise environment.
26
Communicating Exposure Results
The written abstract of sound survey results should
be given to managers and department supervisors, and
the longer summary should be given to the HCP team
members. The updated noise map of the plant should be
explained to employees during their educational pro-grams
and posted for employees to refer to. In areas
where hearing protectors are required for all who enter,
warning signs should be posted. Employee TWA esti-mates
must be transcribed onto the audiometric records
for individual employees to aid the audiogram reviewer
in interpreting whether hearing trends are caused by
on- the- job noise exposure.
Checklist for Sound Surveys
Representative TWAs have been determined for
all noise- exposed job classifications.
A noise map of the plant has been posted to show:
1. areas where employees are included in the HCP
2. areas where HPD utilization is required.
Employees have been told the typical noise expo-sures
for their departments during educational
sessions.
HCP team members and department supervisors
have summaries of sound survey results.
Employee TWAs are listed on their individual
audiometric records.
27
5
Engineering and
Administrative Noise Controls
Engineering Controls
If real- world noise sources such as production equip-ment,
fans, and air compressors that overexpose
employees can be quieted so that their contribution to
the employees’ daily TWA is no longer important, and if
the cost of controlling the sources is less than the cost of
not controlling them, then the noise problems should be
controlled. However, real- world situations are seldom
clear- cut. Making management and engineering deci-sions
concerning the anticipated effectiveness and cost
of noise control options is often a challenge to all parties
involved ( managers, equipment manufacturers, OSHA
personnel, and consultants).
For example, consider a situation where a long- term
financial benefit would result ( increased production and
lower cost per unit produced) if known noise control
solutions for a piece of production equipment were
installed. It is also known that installing noise controls
would lower the employees’ TWA by at least 5 dB( A).
However, the capital to carry out the modifications is
not available. Therefore, in this situation the monetary
constraints would delay known noise control options in
favor of the utilization of hearing protection until the
company is financially able to make the necessary
equipment modifications. Management should recognize
that failure to make the changes as soon as practical
would reduce the company’s ability to compete in the
free market.
28
What is management’s responsibility with respect to
the engineering and/ or administrative noise control
phase of the HCP? For any plant site, management has
the responsibility to identify the dominant noise sources
in all production areas and determine if practical noise
control options are available and if the cost of noise con-trols
is justified. It is not adequate for management to
say, prior to conducting the engineering noise control
survey, that production equipment A is the noise prob-lem
and no solution exists. It might be that uncon-trolled
air exhaust or an improperly installed hydraulic
valve, both problems that are often easily controlled,
are the only major noise sources creating the overexpo-sure
for the operators of the equipment. Whereas iden-tifying
the dominant noise sources in a production area
is typically easy to do, determining the reasonableness
of the anticipated cost is more difficult.
Identifying Dominant Noise Sources
During the basic or detailed sound survey, the sur-veyor
should have identified the obvious dominant noise
sources in the room. This information is now used as
the starting point for the engineering noise survey,
which will determine the contribution of each dominant
source to employee noise exposures.
Using a sound level meter, the surveyor can measure
the sound levels at the employee’s workstation as individ-ual
pieces of equipment in the production area are run
separately, to determine their relative contributions. In
some circumstances it is not practical to run individual
pieces of equipment ( due to continuous equipment opera-tion
and/ or equipment interdependence). Then it will be
necessary to conduct the survey during the yearly main-tenance
period or to make measurements at times when,
due to equipment failure or temporary equipment shut-downs,
one or more of the production units is not operat-ing.
Once the noise levels at the employees’ work stations
are known with different units in operation, then the
29
effective contribution of each piece of equipment can be
easily determined. For more information, see References,
item 5.
Contributing Equipment Noise Sources
Once the dominant noise sources have been defined,
the next step is to determine the significant contribut-ing
noise sources within each piece of equipment.
Typically this survey involves a team consisting of
equipment operators, a mechanic, and a sound survey-or.
As far as the machinery design will allow, individual
components of the equipment are operated and the
noise levels at the employee’s workstation are recorded
for each operating condition. The ideal situation occurs
when one component of the equipment is found to be
the only significant sound source and a readily avail-able,
inexpensive noise control solution exists.
One Example
In a production room the measured TWA of stamping
machine operators was 93 dB( A), and TWAs of 88 dB( A)
were measured for employees in another area of the
room who were packing the product. ( Note that the
level of the noise in the room was constant and roughly
equal to the predicted OSHA TWA.) For employees
working in both areas, noise exposures were below 80
dB( A) when the stamping machines were not running
but the heating, ventilating and air conditioning
( HVAC) system was in operation. Therefore, it was con-cluded
that the dominant noise sources in this produc-tion
room were the stamping machines.
The next step was to operate one stamping machine
while the remaining machines were not running. Due to
production constraints, this required the sound testing
to be carried out between second and first shifts. The
survey team consisted of the company’s chief mechanic
and the sound surveyor.
30
The stamping machine could be run without any
product being stamped, and the air supply used to
assist in the removal of the product could also be turned
off. Therefore the test sequence followed involved run-ning
the stamping unit with the air supply turned off
and without product ( condition 1), then with the air
supply on but without product ( condition 2), and finally
turning out product with the air on ( condition 3). For
condition 1 the measured sound level at the employee’s
work station was less than 80 dB( A). When the air was
turned on ( condition 2), the sound level increased to 90
dB( A). Finally, for condition 3 the sound level increased
by 0.5 dB( A) to 90.5 dB( A). Note that if the addition of
the product ( condition 3) had contributed as much to
the measured noise level as did the air supply ( condi-tion
2), then the increase in level for condition 3 would
have been 3 dB( A). Because the increase was only 0.5
dB( A), it was concluded that the contribution from run-ning
product was at least 10 dB less than the contribu-tion
of the basic machine components plus the air noise.
After identifying the air exhaust system of the stamp-ing
machines as the room’s major contributing noise
source, management had the information to determine
the feasibility of controlling the noise to reduce employ-ees’
exposures. Since the measured sound level at the
operator’s work station was 90.5 dB( A) with only one
stamping machine running, and the workstation level
increased to 93 dB( A) with all units in operation, then
the increase of 2.5 dB( A) was due to the contribution of
the remaining stamping machines. In other words,
noise controls needed to be applied not only to the oper-ator’s
own machine, but also to all other surrounding
units, to reduce the noise level at the employee’s work
station to below 85 dB( A).
31
Many common noise problems, such as air exhaust noise, are simple to
control with commercially available mufflers.
In this case a solution was both economically and
technically feasible. For expenditure of less than $ 15.00
per stamping machine, management was able to com-pletely
eliminate the noise hazard to below OSHA
requirements. Without the engineering noise control
survey, however, management would not have had the
information necessary to make the appropriate decision.
Feasibility Considerations
When conducting the engineering noise control surveys,
several pieces of production equipment are commonly
found to be dominant noise sources, contributing about
equally to the employee’s daily TWA. Each of these domi-nant
noise sources may have included several equally con-tributing
component noise sources. Even when feasible
solutions are known for some of the contributing sources,
the existence of multiple sources may make it possible to
conclude that controlling the employee’s noise exposure
32
cannot be economically justified. However, the pieces of
production equipment that are the dominant sound
sources and their internal contributing noise sources must
first be identified. Otherwise, management will not have
the necessary technical information to accompany other
information ( such as effects on production and cost) upon
which to base appropriate decisions concerning controlling
the noise through engineering means.
Administrative Controls
The most common interpretation of the term “ admin-istrative
controls” includes the use of changes in
employees’ work schedules and job tasks to reduce the
noise exposures for individuals. Many people consider
the purchase of quieter new equipment to be an engi-neering
noise control. However, such “ buy quiet” efforts
are more of a managerial decision than an engineering
effort, since the purchaser transfers the responsibility
for engineering out the noise to the equipment manu-facturer.
To distinguish the application of retrofit noise
controls in the local plant from “ buy quiet” programs,
the purchase of quieter new equipment is interpreted
here as an administrative noise control. Also considered
here to be an administrative noise control is manage-ment’s
establishment of regular maintenance programs
to keep noise levels down by ensuring that both machin-ery
and its noise control features are kept in good condi-tion.
No matter which term the reader chooses to apply
to these noise control strategies— engineering controls
or administrative controls— the goal is the same: to
reduce employees’ noise exposures.
Controlling Employee Work Schedules
Work schedules may be modified in order to limit, or
control, the employees’ noise exposures. In a few special
situations the use of administrative controls has not
only significantly reduced employees’ TWAs but also
increased productivity by sharing a very demanding
33
task between two individuals. In one instance the oper-ator
[ TWA of 89 dB( A)] and oiler [ TWA less than 80
dB( A)] for a large dragline operation, who typically
worked 12- hour daily shifts, were both retrained and
allowed to change work positions every three hours.
Although the oiler’s salary had to be increased, the
resulting increase in productivity offset the cost of high-er
pay for the oiler, and both employees benefited from
reduction of their TWAs to less than 85 dB( A).
However, caution is advised in using administrative
options when they involve exposing a previously unex-posed
population [ TWAs less than 85 dB( A)] to poten-tially
damaging noise levels in order to reduce the
TWAs for a population that is already noise- exposed. In
general it is not good safety practice to increase the per-centage
of the workforce exposed to a known hazard.
Maintaining an Acceptable Maintenance Program
To prevent the noise produced by existing equipment
( newly purchased or modified by engineering controls)
from increasing significantly, a regularly scheduled equip-ment
maintenance program should be in place. It is com-mon
to control a noise problem by engineering means
only to return months later and find that the installed
noise mufflers, equipment enclosures, and vibration isola-tors
have failed to maintain the controlled level of noise
due to either sabotage, inappropriate equipment utiliza-tion,
or inadequate maintenance. Management has the
responsibility to ensure that equipment that has been
controlled for noise output is properly serviced and
utilized in order to maintain the controlled level of noise.
Management typically does not realize that equipment
that has been controlled for noise output must become a
part of a regular noise control equipment maintenance
program. Company engineers and noise control consul-tants
estimate that 2– 4 percent of the cost of noise control
will have to be spent yearly in maintaining the level of
noise reduction originally achieved.
34
It is important to require the active participation of
all involved parties ( such as equipment operators,
supervisors, and mechanics) in maintaining the produc-tion
equipment in a satisfactory condition. Management
directives and the regularly scheduled company educa-tion
program best achieve this goal.
Planning for Noise Control Purposes
A very effective use of administrative controls
involves long- term planning ( less than five years to
start of implementation) for a significantly quieter work
environment. It should be obvious to all by now, after
more than 20 years of OSHA, that in a high percentage
of noisy production environments there is no quick solu-tion
to the noise problem.
In these instances one solution is the purchase of new
equipment, or remodeling of existing equipment or facil-ities,
with sufficient guarantees of a noise- free or signif-icantly
reduced noise environment ( TWA reduced by 10
dB( A) or more). Notice that earlier a significant reduc-tion
in the noise environment was defined as 5 dB( A).
However, due to the problem of estimating noise envi-ronments
for new production facilities, a planned reduc-tion
of 10 dB( A) should guarantee at least a 5 dB( A)
reduction after equipment installation.
Noise Limits for Equipment Purchases and/ or
Modifications
A second effective use of administrative controls is
enforced equipment noise specifications for purchasing
new equipment or modifying existing equipment. Notice
that we emphasize “ enforced” because the clear tendency
in industry is for management to establish noise specifi-cations
that are regularly passed over by purchasing
agents for less expensive alternatives, regardless of the
cost differential.
35
Solving Noise Control Problems Using
In- House Personnel
The preceding discussions of noise controls have been
aimed primarily at defining the more obvious noise
problems. Once these problems have been defined then
management must decide the route to take in achieving
an engineering solution if appropriate. For the simpler
noise problems, in- house solutions are normally more
cost effective.
Purchasing quiet equipment to replace old machines or to outfit a new
facility can eliminate the noise exposure hazard.
To solve the minor noise problems in house it is nec-essary
to: ( 1) identify the individual who will find and
implement the solution and ( 2) give the individual the
necessary flexibility and authority. The experiences of
industrial personnel clearly show in- house staff do not
need professional training to solve simple noise prob-lems.
Nurses, audiometric technicians, and safety direc-tors
who have received the most elementary training in
noise control concepts have been successful at solving
such problems. Together with the lead mechanic, they
36
have controlled air exhaust noise by installing commer-cially
available mufflers. They have controlled HVAC
fan system noise by purchasing and installing in- line
commercially available noise attenuators. They have
controlled motor noise resulting from improper vibra-tion
isolation by installing appropriate commercially
available mechanical isolators.
Company personnel should not believe that without the
results of the noise control survey, a noise problem cannot
be solved without expensive outside consulting services.
For the more difficult noise problems, however, some type
of outside consultation is almost always necessary. Private
firms specialized in noise abatement offer consultation
services. Additionally, consultation is available through
the Bureau of Consultative Services, Division of Occupa-tional
Safety and Health, North Carolina Department of
Labor. ( See the inside back cover of this publication for the
address and telephone number.)
Sources of Information
For immediate information concerning possible noise
control options, management has several possible
sources including the resource staff of the North
Carolina Department of Labor, trade associations,
insurance carriers, and extension departments at the
local technical college or university. In addition to these
sources, there are chapters and articles, plus several
relatively easy- to- read textbooks ( see References, items
6– 10) and one free journal that publishes an annual
summary of all the manufacturers of noise and vibra-tion
control products ( see Resources, item 3).
37
Checklist for Noise Controls
Engineering noise control survey completed.
Dominant production noise sources identified.
Contributing equipment noise sources identified.
Equipment noise purchase specifications exist.
Noise control maintenance program exists.
HCP education phase includes engineering
controls.
New facility planning includes noise control.
Solution of simple noise problems documented.
38
6
Hearing Protection
Hearing protection devices ( HPDs) are the first line of
defense against noise in environments where engineer-ing
and/ or administrative controls have not reduced
employee exposures to safe levels. HPDs can prevent
significant hearing loss, but only if their utilization is
carefully implemented and supervised. Employees will
not achieve adequate protection if various HPDs are
simply placed onto the tool crib shelf, with the choice of
style and size left up to the employee.
For more information about hearing protection, see
References, items 4 and 11– 12, and Resources, item 4.
Organizing the HPD Phase for Success
HPD effectiveness cannot be achieved without the
enthusiastic and diligent efforts of those who select, fit,
issue, and reissue the protectors. Management must
choose capable and interested personnel to handle the
HPD phase. Those selected should be provided with the
knowledge they need to do a good job. Working with the
employee in selecting optimal HPDs and training the
employee to wear and care for HPDs are much more
complicated tasks than dispensing safety glasses, for
example. Therefore, those responsible for HPDs need
detailed education from the HCP supervisor, from
attending a CAOHC course, or from materials and
workshops sometimes provided by HPD manufacturers
and associations concerned with hearing conservation.
HPDs will not protect employees unless their proper
utilization is absolutely enforced as a condition of employ-ment.
Many companies have written disciplinary rules for
failure to wear HPDs, but they are never implemented.
For the HCP to be effective, management must set the
39
same priority on HPD utilization as on the use of all safety
equipment and then back it up with action: the employee
either wears HPDs in required areas or goes home.
Types of HPDs
Earplugs
The most popular HPDs are earplugs, which are
inserted into the ear canal to provide a seal against the
canal walls. Preformed earplugs are made of flexible,
vinyl materials and often come in different sizes to fit
different sizes of ear canals. Formable earplugs are
made of materials that can be manipulated to conform
to the shape of the wearer’s ear canals. The best
formable earplugs are made of foam, which is com-pressed
for insertion into the ear canal, then expands to
fill the canal and seal against its walls.
Earmuffs
Sometimes called circumaural HPDs, earmuffs
enclose the entire external ears inside rigid cups. The
inside of the muff cup is lined with acoustic foam ( which
must not be removed), and the perimeter of the cup is
fitted with a cushion that seals against the head around
the ear by the force of the headband. In most industrial
environments earmuffs are less popular than earplugs,
but they can provide reliable protection.
Semi- Aurals or Canal Caps
These HPDs are small stoppers that seal against the
entrance to the ear canal by the force of a band worn
under the chin or behind the neck. They generally pro-vide
less protection than earplugs or earmuffs. They are
most suitable for short- term use, as they are less com-fortable
than other HPDs for all- day wear.
40
41
Formable foam earplugs
expand to fit ear canals of
different sizes and shapes.
Preformed earplugs may
come in from one to five
sizes to fit different ear
canals.
Earmuffs cover the ear to
block out noise.
Semi- aural HPDs or canal caps are
convenient for brief periods of
noise exposures.
Hearing Protector Attenuation
All HPDs attenuate noise by creating a seal that pre-vents
sound from entering the ear. Earplugs mainly
seal against the wall of the ear canal, while semi- aurals
seal against the entrance to the ear canal or its outer
edge, and earmuffs seal against the head all around the
external ear. In each case the amount of sound reduc-tion
achieved depends largely on the completeness of
the seal— any air leaks will allow some sound to bypass
the HPD.
The maximum achievable attenuation is limited by
the bone- conducted sound that results when sound
vibrates the skull. However, bone- conducted sound
transmission is not important for industrial environ-ments
compared to the effect of whether the HPD is fit-ted
properly and used correctly. In practice, when
employees do not receive adequate protection from their
HPDs, it is because they do not achieve an adequate
seal. This may happen because the HPD does not fit
properly ( the HPD is the wrong size or design for the
individual) or is not used correctly by the employee ( due
to inadequate training or carelessness).
The Noise Reduction Rating ( NRR)
HPD manufacturers publish attenuation data for
their products based on idealistic laboratory measure-ments.
The NRR shown on the label of the HPD pack-age
is intended to give a single- number rating of the
laboratory attenuation across a range of frequencies.
The NRR is subtracted from the employee’s noise expo-sure
to indicate the maximum exposure reduction that
could be attained if the employee had similar physical
characteristics as the laboratory subjects and could
wear the product in the same way as the laboratory
subjects.
The NRR is designed to be subtracted from the
C- weighted sound pressure level to give the A- weighted
level under the HPD:
[ Noise level, dB( C)] – [ NRR] =
[ estimated exposure, dB( A)]
If only A- weighted exposure is known, then a correc-tion
factor of 7 dB must be subtracted from the NRR:
[ Noise level, dB( A)] – [ NRR – 7] =
[ estimated exposure, dB( A)]
The 7- dB correction factor is needed with A- weighted
levels because the dB( A) value gives no indication of
42
whether the energy in the noise environment is predom-inately
low- frequency or high- frequency, and HPDs pro-vide
less protection at lower frequencies. Most dosime-ters
predict only noise dose or equivalent TWA values
based on A- weighted sound pressure levels. However, if
the sound surveyor measures both dB( A) and dB( C)
levels with a sound level meter, then the average “ C
minus A” difference for the noise environment can be
used as the correction factor in place of 7 dB. In high-speed
textile spinning, for example, “ C minus A” differ-ences
ranging from 2 to – 1 dB have been measured.
Real- World Attenuation
Although the NRR is a readily available number that
appears as if it should allow the HPD selector to decide
whether a protector is adequate, it is flawed by the labora-tory
test conditions used to obtain it. Real- world users do
not achieve the amount of attenuation indicated by the
NRR. In general, HCP personnel can count on properly
trained and motivated HPD wearers receiving about 50
percent of the NRR value in attenuation. Very motivated
users can achieve better results. ( See References, item 12).
The NRR cannot even be used to rank the real- world
effectiveness of HPDs. Studies in which employees were
pulled off the job to have their actual HPD attenuation
measured have shown that the attenuation achieved
with different HPDs gave a different rank from their
NRRs. Products that are more “ goof- proof” ( foam
earplugs and earmuffs) provided higher real- world
attenuation than other HPDs ( see References, item 12).
Because the NRR is not a realistic indicator of the
attenuation that wearers achieve, HCP personnel should
not use the NRR as a significant criterion for evaluating
HPDs. Comfort, convenience, and compatibility with the
working environment ultimately determine the protec-tion
an employee will receive from a hearing protector,
since the effective attenuation of an unworn HPD is zero.
43
Purchasing Appropriate HPDs
It is essential to select and keep in stock a sufficient
choice of HPDs appropriate to the work environment
and the wearers’ needs. Generally an adequate selection
would include three types of earplugs, two styles of ear-muffs,
and one semi- aural device.
The choice of HPDs should be made by the HCP per-sonnel,
based on characteristics of the work environ-ment
and real- world HPD performance as well as the
preferences of the employees. The purchasing depart-ment
must not be allowed to overrule the HPD selec-tion.
Management should give HCP personnel the
authority to obtain the HPDs they feel are best for the
company’s workforce. The factors that should be consid-ered
in choosing HPDs the company will stock are dis-cussed
in the following paragraphs.
Real- World Attenuation
Because most employees have noise exposures below
a TWA of 95 dB( A), they only need 10 dB of real- world
attenuation. Most HPDs can provide this much protec-tion,
if properly fitted and correctly worn. Higher
employee TWAs require more careful HPD selection,
and only the protectors with the best real- world attenu-ation
( earmuffs or foam earplugs) are recommended for
TWAs of 100 dB( A) or above.
Comfort
Employees will not wear uncomfortable HPDs, so the
goal of fitting is to find the most comfortable HPD that
gives adequate protection for the environment. Because
44
The best HPD is the one
the employee will wear
consistently and correctly!
no single HPD suits all wearers, several choices should
be available. The employee should be allowed to select
his or her preferred HPD as long as the issuer confirms
that the fit is adequate for the required attenuation.
Convenience
Employee acceptance of HPDs depends on practical
factors such as:
✦ Ease of correct positioning considering physical
limitations of the wearer ( such as finger size or
strength, arthritis)
✦ Speed and ease of HPD removal and repositioning
✦ Simplicity of carrying or storing during work breaks
✦ Compatibility with other safety gear ( masks, hard
hats)
✦ Suitability for job tasks ( crawling in tight spaces,
strenuous physical activity, repetitive head move-ments)
✦ Practicality in the physical environment ( for exam-ple,
considering heat, dirt, chemicals)
Each employee needs to be shown how to insert earplugs or wear ear-muffs
properly to achieve a good seal and adequate protection.
45
Communication Needs
Select a HPD that will allow the employee to commu-nicate
as required in the workplace noise environment.
For normal- hearing employees, this is usually not a
problem since HPDs improve speech discrimination in
noise above 90 dB( A) by reducing distortion in the ear
from high sound levels. However, for workers with pre-existing
hearing loss, HPDs often make communication
more difficult by reducing speech- sound information to
below their hearing thresholds. Hearing- impaired
employees who must receive detailed face- to- face
instructions may prefer earmuffs so that they can lift
up the earmuff cup to hear speech, or plugs with mini-mal
attenuation may improve reception of speech as
well as auditory warning signals. Hearing- impaired
employees may also benefit from the new HPDs
presently being developed that exhibit flat attenuation
across the frequency spectrum. These HPDs provide
less reduction than regular HPDs of the high- frequency
sounds that are affected most by hearing loss.
Employee Input
HCP personnel need to solicit employee opinions
about various HPD products. This can be done by con-ducting
wearer evaluation trials, by asking for employ-ee
feedback in safety meetings and in the break room or
cafeteria, and by questioning individuals when HPDs
are reissued or when the annual audiogram is adminis-tered.
HCP personnel should be aware of new HPDs
that might be suitable additions to or replacements for
the HPD choices currently carried in stock. When
employees ask about products they have seen, if practi-cal,
the HPD issuer should investigate these options.
46
Maximizing the Effectiveness of HPDs
in Actual Use
The attention paid by the HPD issuer to the following
factors will determine how much real- world protection
employees receive from their HPDs.
Correct Fit
HPDs offer little or no protection if they do not form a
seal to block out sound. All HPDs must initially be fitted
by a trained issuer. Earplugs must be fitted separately in
each ear, as an individual’s two ear canals may differ in
size or shape. Because none of the “ universal- fit” plugs
can actually fit every individual, even one- size earplugs,
including foam earplugs, must be checked for proper fit
in both left and right ears. Pamphlets about selecting
and fitting HPDs are available from National Hearing
Conservation Association ( see Resources, item 6).
Good HCPs always stock premolded plugs in a full
range of sizes to suit extra small and extra large ear
canals. Before inserting an earplug into the employee’s
ear, the fitter must visually cheek the ear canal for excess
wax or obvious abnormal conditions that would require fit-ting
to be delayed until the problem is corrected. The fit of
earmuffs also must be checked for each wearer to make
sure that the earmuff cushion seals against the head all
around the ear, and that the outer ear ( pinna) can fit
inside the cup ( the cushion must not rest on the pinna).
Training Users
Each HPD wearer must receive specific instructions on
how to wear and care for the HPD issued. To ensure that
47
There is no such thing as
a “ universal- fit” HPD!
the employee can insert or place the HPD correctly, the
fitter should watch while the individual user demon-strates
how to put on the HPD correctly. If the employee’s
initial attempt is inadequate, the fitter should reinstruct
and have the worker practice in the fitter’s presence until
proper placement is achieved. Employees must be con-vinced
that they will not receive adequate protection
unless they correctly wear and maintain their HPDs. The
employee needs to know the signs of HPD deterioration
that indicate it is time to get a replacement. Each year
the employee should be asked to bring his or her HPDs to
the audiometric evaluation so that the fitter can inspect
them for wear, reevaluate the fit, and check that the
employee can still place them correctly.
Responding to Wearer Questions and Complaints
HPD issuers must be open to employee concerns.
Issuers should seek answers to employees’ questions
and work individually with employees who find it diffi-cult
to wear HPDs because of discomfort or the inability
to communicate adequately while wearing them.
Controlling the HPD Replacement Process
HPD reissuers need to maintain strict control of
replacements so that employees are reissued only the
style and size of HPD indicated on the fitting record.
Employees who wish to change HPD type or size must
return to the fitter for refitting.
Replacing HPDs Regularly
New HPDs should be routinely issued to each wearer
on a schedule appropriate for the type of HPD being
worn. An aggressive replacement procedure will pre-vent
employees from retaining HPDs that have lost
their effectiveness. At the same time HCP personnel
can detect altered HPDs and reeducate the employees
who made alterations. Some key individuals periodical-ly
set up an HPD replacement station at the plant exit
during shift changes as an extra reminder.
48
Monitoring HPD Utilization
Front- line supervisors and production department
heads need to perform regular checks to ensure that
employees are properly wearing their HPDs. Employees
who do not cooperate with the mandatory HPD utiliza-tion
policy must receive reeducation and meaningful
disciplinary actions, eventually culminating in dis-missal
for repeated offenses. At the same time, consis-tent
HPD users should be rewarded for their perfor-mance
through recognition for departments with good
utilization records and by praise for individual wearers.
Motivating Employees to Wear HPDs
Effectively
Ultimately, the employee who wears the HPDs is per-sonally
responsible for achieving and maintaining protec-tion
from noise through the proper use of HPDs. However,
the employer must educate and motivate the employee to
take this active part in the HCP. The key individual and
other HCP team members should strongly consider
employees’ input when selecting the HPDs to be stocked,
as well as when finding a suitable protector for an indi-vidual.
Employees need clear, understandable informa-tion
to help them appreciate that they will be protected
from developing hearing loss only if they consistently and
correctly wear HPDs that are fitted properly.
Identifying Satisfactory HPDs
The employee and the fitter need to work together to
select a product that will be comfortable and convenient
enough for the worker to wear it consistently. The
employee who has received proper education will under-stand
that some initial discomfort is expected during
the breaking- in period when getting used to HPDs. If
the employee still encounters significant discomfort or
interference with job tasks after one to two weeks of
wearing a new HPD, then the wearer should return to
the fitter to request another type.
49
Wearing HPDs Correctly and Consistently
Ultimately employees must accept the responsibility
to reduce their noise exposure by faithfully and properly
wearing HPDs both on and off the job. Intermittent or
incorrect HPD use will not prevent the development of
noise- induced hearing loss. The department supervisors
can ensure that all employees in HPD- required areas
are wearing HPDs, and the HPD fitters can spot- check
in each department for actual correctness of HPD fit and
placement. Annually, at audiogram time, each employee
should be retrained in proper HPD fitting, use, and care.
Caring for and Replacing HPDs
Employees need specific instructions as to how to: wash
their HPDs, store them in cases or safe places to prevent
damage, inspect them for signs of wear and tear, and seek
replacements when deterioration occurs. Employees must
be taught that achieving good protection depends on keep-ing
the HPDs in good condition. Worn- out or intentionally
altered HPDs will not provide adequate attenuation.
Demonstrating Management Support
Managers must demonstrate support for HPD utiliza-tion
and emphasize its importance by:
✦ Wearing HPDs each time they enter an area with
either a voluntary or mandatory HPD wearing pol-icy
( no matter for how brief a time the managers
are in the area)
✦ Establishing a policy of mandatory HPD utilization
✦ Making HPD utilization enforcement part of the
basis for performance ratings of the front- line
supervisors and production department heads
✦ Providing a mechanism for regularly praising or
rewarding employees who wear HPDs correctly
and consistently
50
✦ Rating the performance of all personnel responsi-ble
for any aspects of HPD utilization enforcement,
fitting, issuing, and replacement
✦ Directing that HPDs be made available to employ-ees
for off- the- job noise exposures so that hearing
will be protected around the clock
✦ Purchasing equipment to allow HPD issuers to
monitor the field performance of HPDs as actually
used by individuals
✦ Scheduling regular meetings among the HPD fit-ters
and issuers, the reissuers, and the supervisors
who enforce utilization on a daily basis
Shooting is one of the most common causes of off- the- job noise-induced
hearing loss, but hearing protectors are very effective against
gunfire noise.
51
Checklist for Hearing Protection
HPD utilization in required areas is strictly and
consistently enforced.
Comfort, practicality, and real- world attenua-tion—
not the NRR— are the primary criteria for
selecting which HPDs will be stocked.
Each employee is individually fitted with HPDs
and trained in their proper use and care.
Fit is checked for all types of HPDs, including ear-muffs
and single- size earplugs.
A minimum of two earplugs ( one in multiple sizes)
and one earmuff are available for selection, but
preferably three plugs, two muffs, and one semi-aural.
HPDs are replaced on a regular basis.
HPD reissuers distribute only the type of HPD fit-ted
to each employee; to change types or sizes the
employee must return to the fitter.
Each employee’s HPDs are rechecked during the
audiometric evaluation for condition, fit, and cor-rect
placement.
Employees are given HPDs to take home for use
during off- the- job noise exposures.
52
7
Audiometric Evaluations
The audiometric evaluations phase of the HCP ties
together all the other phases by indicating whether the
program’s goal is being achieved: prevention of on- the- job
hearing loss. If the HCP is not effective, the result will be
seen as worsening hearing thresholds for employees, as
well as a higher percentage of the noise- exposed popula-tion
showing an OSHA standard threshold shift ( STS).
One consequence is an increase in the company’s poten-tial
liability for compensable occupational hearing loss.
When audiograms detect temporary threshold shift,
early permanent threshold shift, or progressive noise-induced
hearing loss, the HCP personnel are alerted to
take swift actions to halt the loss before the employee’s
hearing shows a significant deterioration. Because
noise- induced hearing loss typically occurs so gradually,
the affected individual may not notice the slow change
until a large threshold shift has accumulated. Audio-metric
monitoring can identify individuals who are
inadequately protected so that they can be retrained
and/ or given better HPDs and extra motivational atten-tion
to prevent further loss.
However, audiometric evaluations cannot provide
reliable data to guide intervention unless they are con-ducted
under adequate quality standards and the
results are appropriately evaluated and meaningfully
communicated to the employee. For more details about
the audiometric phase, see References, items 13– 15.
Management Support Needed for Quality
Managers must support the audiometric evalua-tions
phase by funding quality services. Because
audiometry requires a substantial investment of
53
money and personnel time, it is cost- effective to allo-cate
enough resources to ensure that the desired ben-efits
are obtained from audiometric monitoring.
Otherwise, the money is simply wasted on deficient
services that do not serve their intended purpose of
alerting HCP personnel to take actions that will pre-vent
hearing loss.
54
Normal Audiogram
and Degrees of Hearing Loss
SLIGHT
MILD
MODERATE
MODERATELY SEVERE
SEVERE
PROFOUND
– 10
0
10
25
40
55
70
85
100
Hearing Threshold Level, dB
Frequency, Hertz
500 1000 2000 3000 4000 6000
Low Pitched
Sounds
High Pitched
Sounds
The audiogram shows hearing thresholds for tones at dif-ferent
pitches or frequencies. Normal thresholds fall within
the unshaded area of the chart. If noise- induced hearing
loss begins to develop, the thresholds for the higher fre-quencies
( 3,000– 6,000 Hz) will start to fall into the shaded
areas.
• • • • • •
In- House versus Contracted Services
Managers may choose to contract for employee audio-grams
to be performed by an external source ( a mobile
testing contractor or a local clinic). Alternately, manage-ment
may purchase audiometric equipment and train
internal personnel to perform audiograms under the
supervision of an audiologist or qualified physician. The
choice depends on factors including the company’s phi-losophy
about safety and health, as well as its size and
geographical location. Our experience indicates that the
audiometric phase will be much more effective in moti-vating
employees if their audiograms are performed
and discussed with them by in- plant HCP personnel. If
external services are used, it is critical that manage-ment
assign responsibility to the on- site key individual
for making sure that quality services are obtained and
for using the audiometric results to motivate employees.
Well- Qualified Personnel to Perform Audiograms
The audiometric technicians should hold current
CAOHC certification as occupational hearing conserva-tionists.
Additionally, all technicians should use consis-tent
testing methods under the supervision of an audi-ologist
or qualified physician.
Adequate Time Allowed to Complete Evaluations
If the audiogram session is to achieve its potential for
motivating the employee about hearing conservation,
there must be adequate time for that purpose. The tech-nician
needs sufficient time to obtain auditory history
information, inspect HPD condition and fit, properly
instruct the employee, carefully administer the audio-gram,
briefly explain the results to the employee, and
document the findings. When the technician is too hur-ried
to do more than give a rapid screening audiogram
and herd the employee out the door, the worker correctly
perceives that the testing is performed only for OSHA
compliance without any sincere interest in protecting
55
hearing. In this case the employee will usually lose moti-vation
to participate in the HCP.
Obtaining All Needed Information
The OSHA regulations do not require measurement
of hearing thresholds at 8,000 Hz or the documentation
of auditory history information ( details about the
employee’s off the job noise exposures, medical condi-tions
affecting hearing, the presence of ringing in the
ears, and other associated information). However, the
wise employer will include both of these features in
employees’ audiometric evaluations because they allow
the reviewer to interpret the audiogram results with
more confidence and may eliminate a number of costly
medical referrals. The 8,000 Hz thresholds assist the
reviewer in distinguishing between age- related hearing
change and noise- induced hearing change. The auditory
history information assists the reviewer in deciding
whether observed hearing change is probably related to
on the job noise exposures, or whether off- the- job causes
may have contributed.
Regular Schedule of Audiometric Monitoring
For maximum protection of the company and employ-ees,
audiograms should be performed at pre- employ-ment
or prior to initial assignment to a noisy work area.
Thereafter, audiograms should be performed annually
for as long as the employee is assigned to a noisy job ( or
twice a year during the first two years of exposure for
workers with TWAs over 100 dB( A)). The company
should also perform an audiogram when the employee
is reassigned out of a noisy job and at the termination of
employment.
Many companies have found it is desirable to give
audiograms, as a health screening benefit, every one to
three years to employees without on- the- job noise expo-sure.
Annual audiometric results for nonexposed
employees also serve as a control group when using
56
audiometric data base analysis to evaluate the HCP’s
effectiveness, as discussed in the final section of this
publication.
Careful Choice of a Professional Reviewer
Management should ensure that the program super-visor
who reviews employees’ audiograms is a well- qual-ified
professional with specific training and experience
in the area of industrial hearing conservation. Such a
choice will benefit the employer as well as the employ-ees,
as an experienced audiologist or physician is less
likely to mistake nonoccupational loss as being job-related.
Feedback and Follow- up
The audiometric session is the greatest opportunity
to motivate employees concerning hearing conservation.
Management should allow an extra two minutes for the
audiometric technician to give the employee simple,
brief remarks about his or her hearing status immedi-ately
after the audiogram is completed to praise the
worker or warn that better HPD utilization is needed.
All employees ( not just those with threshold shifts)
should receive written feedback from the professional
reviewer. When the reviewer points out potentially
noise- induced hearing changes, company personnel
need to take decisive follow- up actions. These actions
include individual counseling, refitting and retraining
for HPD utilization, encouraging the employee to wear
HPDs during off- the- job noise exposures, and more
careful supervision of on the job HPD use. When the
reviewer indicates that the shifts appear unrelated to
noise exposure, the employee should be urged to seek
otological/ audiological evaluation and treatment. If
audiograms are filed and forgotten rather than used to
guide follow- up actions, then the audiometric phase
simply documents hearing loss as opposed to helping
prevent it.
57
Quality Control Responsibilities of
Audiometric Technicians
The accuracy and usefulness of the audiogram results
depend on the care and attentiveness of the audiometric
technicians.
Maintaining Test Equipment and Environment
Audiogram accuracy depends on the audiometric
technicians performing and documenting daily calibra-tion
checks and self- listening checks of audiometer
function. If an electro- acoustic blockhead device is used
to check calibration of audiometer output levels, the
technician must still listen through the earphones for
signal distortion or erratic responses that the device
cannot detect. A log of biological and/ or electro- acoustic
output checks and listening checks of audiometer func-tion
should be maintained.
To measure thresholds accurately for employees with
0- dB hearing levels and to ensure that company audio-grams
are acceptable for legal purposes ( such as workers’
compensation claims), the test room must be quiet
enough to meet ANSI standard S3.1- 1991. That standard
requires lower background levels than the OSHA Hearing
Conservation Amendment. The technician should periodi-cally
check and document background levels.
Acoustic and exhaustive audiometer calibrations should
be scheduled regularly, but calibration services should not
be allowed to adjust the audiometer unless it fails to meet
calibration tolerances. Unnecessary annual adjustments
typically add seesaw variability to the audiometric data,
interfering with the interpretation of both individual and
group hearing trends. If audiometer adjustments must be
made because tolerances are exceeded, the calibration
company must be required to provide both preadjustment
and post- adjustment measurements so that the size and
direction of changes will be documented.
58
Another source of measurement variability can be
prevented by using the same audiometers consistently.
Technicians should not switch back and forth between
types of audiometers ( manual, self- recording, and
microprocessor audiometers).
Using Consistent Instructions and Testing Methods
All audiometric technicians should use the same
standardized testing method under the supervision of
an audiologist or qualified physician. If technicians do
not place the earphones carefully to line up the ear-phone
speakers with the employee’s ear canals, then the
measured thresholds may be in error; therefore, never
allow employees to place the earphones themselves.
When technicians differ in their response instructions
to employees or their signal presentation and threshold
recording methods, the excess variability in threshold
measurements interferes with interpretation of hearing
trends. It is very important to instruct employees to lis-ten
carefully and respond to the faintest tones they can
just barely detect— rather than waiting until tones are
loud and clear before responding. ( The wording of the
instructions can be adjusted to whatever vocabulary
seems most meaningful to the employees, but this con-cept
of listening for faint tones must be communicated.)
Because hearing thresholds may improve over time, the
audiometric technician must try to measure the best
thresholds for the employee, not just duplicate the
results of the last test.
Maintaining Complete Records
The audiometric record should indicate the specific
equipment used, calibration date, the name of the tech-nician,
the date and time of the test, and the threshold
values obtained. The technician’s judgment of the sub-ject’s
response reliability, the HPD inspection results
and refitting or reissuing record, the employee’s TWA,
and the technician’s comments should also be recorded.
59
The professional reviewer’s recommendations and docu-mentation
that follow- up actions were carried out
should be documented too.
Annual audiometric evaluations monitor the employee’s hearing
thresholds. If noise- related hearing changes are detected, counseling
and HPD retraining may help achieve better protection.
Scheduling Audiograms
The audiometric evaluations should be scheduled in
close coordination with production supervisors in order
not to disrupt production more than necessary. If super-visors’
needs are ignored, the supervisors will be less
likely to fulfill their HCP responsibility of monitoring
HPD utilization. To minimize the disruptive effect on
departments and to ensure that employees who are
transferred among departments do not accidentally
miss their annual audiograms, it is often useful to
schedule audiograms in the employee’s birth month.
Participation in annual audiometric evaluations should
be a condition of employment, not a choice.
60
The baseline audiogram should be administered
when the employee has not been exposed to noise for
the preceding 14 hours. However, annual audiograms
should be administered during the workshift, not before
it, so that the results will detect any temporary thresh-old
shifts in hearing that may be occurring in employees
who are not adequately protected.
Using the Audiogram Session to Best
Advantage
The annual audiogram is often the only predictable
time during the year when the individual employees
have the opportunity for a one- to- one conversation
about hearing conservation and their own hearing sta-tus.
This time is the best chance to motivate workers to
protect their hearing. Whether the technicians are
external ( contract) personnel or internal ( staff mem-bers),
they absolutely must demonstrate enthusiasm for
hearing conservation and sincere interest while per-forming
audiograms and giving feedback to employees.
Auditory History Information
The OSHA regulations do not require maintenance of
auditory history information ( documentation of the
employee���s past noise exposures in the military and in
previous jobs, the employee’s off- the- job noise exposures
such as gunfire or use of power tools, and the employ-ee’s
ear- related medical history). However, it is in the
employer’s best interest to record these data for better
interpretation of the employee’s audiometric results and
for protection against future hearing loss compensation
claims. Updated history information allows the profes-sional
reviewer to make recommendations with more
insight and confidence concerning probable causes for
threshold shifts. In addition, the history questions
remind the employee that off- the- job factors influence
hearing status.
61
Checking HPDs at Time of Audiogram
As previously discussed in the HPD section, the
audiometric technician should check the condition and
fit of the employee’s HPDs, change them if needed, and
reinstruct the wearer.
Immediate Feedback about Hearing Trends
The professional who supervises the audiometric
technician can provide guidelines for the technician’s
comments about employees’ hearing as soon as they
step out of the audiometric booth. That is when they are
most interested in their hearing and most receptive to
suggestions. If hearing thresholds have remained sta-ble,
praise the employee for a job well done. If thresh-olds
appear to be worsening, advise the employee of the
need to determine the causes of the hearing change. For
example, the causes might be medical problems or inad-equate
use of HPDs on or off the job. Note that the pro-fessional
reviewer will provide more detailed written
feedback about the hearing changes.
Following up on Audiometric Results
Every audiometric record must be reviewed to classi-fy
the hearing trends and determine whether other
actions are needed.
Careful Audiogram Review
The supervising professional may set up procedures
for the technician to follow when reviewing routine
records ( those with normal hearing and no shifts or
improvements) and when preparing employee feedback
notices. Alternately, the company may find it easier to
have the professional review the routine records as well
as the problem audiograms. The reviewer needs to look
for significant improvement threshold shifts at any test
frequency ( not just OSHA standard threshold shifts)
and look at audiogram patterns indicative of possible
62
otological pathology. Significant shifts would include a
change of 15 dB at any frequency that is confirmed as
being persistent on a retest, or a change of 20 dB
( whether confirmed or not).
Prompt Meaningful Feedback
The reviewer ( or technicians under professional
supervision) should provide each employee written feed-back
describing the worker’s hearing status in terms of
three aspects:
1. Comparison to the expected age- effect hearing lev-els
for the worker’s age/ sex/ race group and the hearing
ability needed for unimpaired communication
2. A description of the amount of change seen in the
current audiogram compared to past results and the
designated reference baseline
3. Recommendations, including praise for stable
hearing, warnings to use HPDs more carefully on and
off the job if hearing changes are observed, and sugges-tions
to seek medical attention or further audiological
evaluation
Taking Appropriate Follow- up Actions
OSHA regulations specify required follow- up actions
for OSHA STS ( a change of 10 dB in the average
63
All employees need feedback
not just those with OSHA STS!
Audiograms don’t prevent hearing loss
but feedback and follow- up can!
thresholds at 2,000, 3,000, and 4,000 Hz in either ear
after optional corrections for aging). But in effective
HCPs, aggressive follow- up for beginning hearing shifts
will prevent losses from progressing into OSHA STSs.
In an excellent HCP the employee with beginning shifts
will receive a written warning from the professional
reviewer and face- to- face counseling from on- site HCP
personnel based on the reviewer’s comments. Similarly,
there should be reevaluation of HPD adequacy, retrain-ing
in HPD placement, and extra supervision in on- the-job
HPD utilization for such an employee. A retest
audiogram may be given to see if the shifts persist or
disappear. Individuals with potential medical ear condi-tions
will be counseled by the employer to seek medical
evaluation and treatment or possibly be sent for treat-ment
at company expense.
Immediate feedback about the audiogram results can motivate the
employee to protect hearing on and off the job.
64
Educating Employees to Take
Responsibility
As employees become familiar with the audiometric
evaluation process, understand their audiogram results,
and learn how their everyday habits in HPD utilization
can affect their hearing trends, they will be encouraged
to take the lead in protecting their own hearing on and
off the job. No matter how much effort the employer
puts into the HCP, it is impossible to inspect whether
each employee is wearing HPDs adequately each day.
Eventually the individual worker must accept responsi-bility
for following through with good hearing protection
habits. The best tool the hearing conservationist has to
motivate individuals about protecting their hearing is
to counsel them about their audiogram results.
Checklist for Audiometric Evaluations
Audiometers are in good operating condition.
Audiometer calibration is not adjusted unless it is
out of tolerances, and both pre- adjustment and post-adjustment
readings are permanently recorded.
Audiometric technicians use consistent testing
methods under professional supervision.
Technicians instruct employees to listen carefully
and respond to the faintest tones they can detect.
Employees’ auditory history information is updat-ed
annually and provided to the audiogram
reviewer.
Employees receive immediate feedback from the
audiometric technician about audiogram results
as related to HPD use.
65
Employees receive written feedback from the
audiogram reviewer about:
• hearing status compared to normal for age
• hearing change over time
• recommendations for better protection on and
off the job, or for medical examination or treat-ment
if appropriate.
The audiogram reviewer looks for significant
shifts at any frequency, not just for OSHA STSs.
Audiogram reviewers revise employees’ reference
baseline thresholds for threshold improvement as
well as for persistent worsening.
HCP personnel follow through with counseling
and HPD retraining for employees with hearing
change.
66
8
Making Sure
That the HCP Works
The Team Approach
Now that you have reviewed all five phases of HCPs,
take another look at figure 1 and consider the impor-tance
of teamwork in achieving the goal of preventing
hearing loss on the job. No single phase of the HCP
can work effectively in isolation from the others. Many
people are involved: foremen, tool crib clerks, safety
officers, audiometric technicians, nurses, personnel
directors, industrial hygienists, engineers, audiolo-gists,
and physicians. No single discipline can claim
superior ability to run the HCP: the program depends
on the cooperation of many people, under the leader-ship
of the key individual. The key individual can be
anyone with the interpersonal skills and managerial
know- how to coordinate the contributions of these
diverse personnel toward preventing hearing loss. The
key individual is the catalyst who makes the HCP
work by maintaining communication among the team
members to achieve a unified HCP.
Documentation and Recordkeeping
When the OSHA inspector visits, the only way the
company can demonstrate that the HCP is satisfactory
is through adequate documentation of the five phases.
Some people actually refer to recordkeeping as a sixth
phase, but recordkeeping is an integral part of each
phase, not a separate activity. For example, the audio-metric
phase depends on cumulative records to show
hearing changes over time. It also depends on records of
67
auditory history information, employee noise exposure,
and HPD fitting and reissuing to evaluate whether
threshold shifts may be work- related. In addition to the
legal documentation it provides, good recordkeeping is
helpful in monitoring the program and sharing informa-tion
among HCP team members. The key individual
should assign responsibility to HCP team members for
maintaining the records associated with their duties
and should ensure that the records are accessible. A list
of the needed records is shown as table 4, and further
details are provided in References, items 16– 17.
Recording Hearing Loss on the OSHA
200 Form
Occupational hearing loss is recorded on the OSHA
Form 200 either as an occupational illness ( for gradual
hearing loss) or as an occupational injury ( for sudden
traumatic hearing loss). In North Carolina and several
other state OSHA plans, the amount of work- related ( if
work- related) hearing change that must be recorded is
the OSHA standard threshold shift or STS ( a change in
either ear from baseline of 10 dB in the average of hear-ing
thresholds at 2000, 3000, and 4000 Hz, with option-al
corrections for aging). In states under federal OSHA
plans, a work- related change of 25 dB in the average of
thresholds at 2000, 3000, and 4000 Hz must recorded.
However, since 1996 federal OSHA has been consider-ing
changing this 25- dB value to a smaller amount of
shift, so this requirement may be updated. Numerous
professional associations have supported logging work-related
age- corrected shifts of 10 dB ( see docket testi-mony
for 1996 OSHA hearings on recordability, as well
as the AIHA position statement published in the
American Industrial Hygiene Association Journal, vol.
57, pages 661– 662, 1996).
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Table 4
Documentation Guidelines for the HCP
69
A. Records Specified in OSHA’s Hearing Conservation Amendment
1. Noise exposure measurements
• Detailed survey report must include complete list of instru-ments
used in survey, calibration, measurement positions,
tables of sound level measurements, and TWA calculations
List departments or employees with TWAs of 85 dB( A) or over
• For OSHA retain 2 years or until new sound survey
• Keep indefinitely for workers’ compensation purposes
2. Documentation of engineering/ administrative noise controls
• results of engineering sound surveys
• installations completed and noise reduction achieved
• regular maintenance of machinery and controls
3. Documentation of annual educational programs, including:
• content of presentation
• names of presenters
• list of employees who attended
4. Documentation of hearing protection phase of HCP:
• date of initial HPD fitting of each employee
• brand and size of HPD fitted ( in each ear if appropriate)
• employee’s signature for training in HPD use and care
• documentation of employer’s supervision of correct HPD use
such as walk- through checks of utilization
• NRR and TWA calculations showing HPD adequacy
5. Employee’s audiometric records, including:
• name, age, job classification, and TWA exposure
• date of audiogram and name of audiometric technician
• audiometer model SN and date of its last calibration
• Retain for duration of employment for OSHA
• Keep indefinitely for workers’ compensation
6. Supporting records for audiometric phase of HCP:
• technician’s certification credentials
• audiometer make, model, and serial number
• audiometer acoustic and exhaustive calibration records
• biological calibration check records of audiometer
• background sound levels in audiometric test room
Assessing Your HCP
The most basic form of program assessment is to use
the checklists provided in this booklet to see whether all
the bases have been covered. Have all the tasks been
accomplished? For example, the key individual might
discover that a group of employees did not attend an
educational program or missed their annual audio-grams.
Just as important is whether the more subjective
70
7. Documentation of audiogram review and follow- up actions:
• review of each audiogram by professional or technician
• credentials of audiologist or physician reviewer
• reviewer’s follow- up recommendations
• documentation that the employer did recommended follow- up
• documentation of employee��s written notification of STS
• employee’s signature indicating OSHA STS follow- up
• documentation of HPD utilization enforcement after STS
B. Additional Records Employer Should Keep for the HCP
1. Audiometric Phase:
• auditory history information for each employee in HCP
• annual history updates
• annual otoscopic checks
• pre- employment or pre- exposure audiograms
• termination audiograms
2. Hearing Protection Phase:
• dates of HPD reissuing, brand and size reissued
• annual documentation at audiogram time that:
• employee’s HPD is correct size, in good condition
• employee can demonstrate proper use of the HPD
• list of HPDs the employer allows to be used in work environ-ments
with different TWA ranges, considering real- world atten-uation
( must derate the NRR)
3. Sound Exposure Monitoring:
• noise map of the facility, showing:
• areas where HPDs are optional
[ TWAs below 90 dB( A)]
• HPD- required areas
[ TWAs = 90 dB( A) or higher]
• areas where only certain HPDs are acceptable
[ TWAs = 95 dB( A) or higher]
guidelines have been met. For instance, has the key
individual made a point to get feedback from the HDP
reissuers and employees concerning the practicality of
the new earplug?
The checklist approach is fine as far as it goes, but it
does not assess the effectiveness of the program, just its
completeness. To evaluate whether hearing loss is really
being prevented, a different approach is needed.
Audiometric Data Base Analysis ( ADBA)
The audiometric results for the noise- exposed
employees provide the only objective indication of
whether the HCP is succeeding in preventing occupa-tional
hearing loss. Reviewing the audiometric records
for employees one at a time detects hearing changes for
individuals, but it does not provide an overall picture of
how well the group of workers is being protected. In
contrast, analysis of group audiometric data can show
the trends for departments and the whole plant.
Over the past several years, the ANSI S12- 12
Working Group for Evaluation of Hearing Conservation
Programs ( see Resources, item 5) has been developing
simple procedures that the employer can apply to the
audiometric data for a group of exposed employees to
assess whether they are being adequately protected.
The advantage of audiometric data base analysis
( ADBA) procedures is that problems in the HCP can be
detected early, before individual workers develop signif-icant
permanent hearing loss. If the results show that
the HCP is ineffective, the employer can improve pro-gram
practices to prevent additional hearing loss from
developing.
71
Audiograms do not prevent hearing
loss but using ADBA results can!
The ANSI S12- 12 Working Group has recently issued
its recommendations for procedures to use in evaluating
the effectiveness of HCPs. The general guidelines and
two of the recommended ADBA procedures are summa-rized
below, and detailed discussions are available. See
References, items 18– 20.
Audiometric Variability as an Indicator
The procedures recommended for audiometric data
base analysis are based on the year- to- year variability
in audiometric thresholds. If you look at the audiogram
results for a person from one year to the next, thresh-olds
at some frequencies may be a little better while
thresholds at other frequencies may be a bit worse.
Variability in audiometric threshold measurements
comes from three main sources:
1. Normal fluctuations in the responsiveness of the
person being tested ( unavoidable variability)
2. Inconsistencies in the equipment and testing
methods used to administer the audiogram ( avoid-able
measurement error)
3. True threshold changes due to temporary or perma-nent
hearing loss if employees receive inadequate
protection from noise ( what the HCP is trying to
prevent)
ADBA looks at the total variability in employees’
hearing threshold measurements. If the variability in
the HCP is in the same low range that is achieved in
low- noise- exposed or nonexposed industrial groups, then
the HCP is judged to be successful in avoiding measure-ment
error and in preventing hearing loss. However, if
variability is too high, then the hearing conservationist
must determine whether the cause is a problem with the
audiometric testing procedures or a real indication of
developing hearing loss resulting from inadequate pro-tection.
Until the variability is reduced, the HCP is
judged ineffective, because unreliable audiometric
72
results may not be capable of identifying actual hearing
loss in individuals.
Recommended Guidelines
Two variability procedures recommended by the
ANSI S12- 12 Working Group are based on counting the
percentage of employees whose hearing shows changes
of 15 dB or more between two sequential ( consecutive)
annual audiograms, such as from test 1 to test 2, or
from test 2 to test 3. Threshold changes are counted
both toward better hearing and toward worse hearing to
yield values for these two ADBA procedures:
1. Percent Worse Sequential (% Ws): the percentage
of employees who show a worsening of 15 dB or
more in thresholds for at least one test frequency
( 500 Hz through 6,000 Hz) in either ear between
two sequential audiograms
2. Percent Better or Worse Sequential (% BWs): the
percentage of employees who show either an
improvement or a worsening of 15 dB or more in
thresholds for at least one test frequency ( 500 Hz
through 6,000 Hz) in either ear between two
sequential audiograms.
Based on applying these procedures to the audio-metric
data for over 20 industrial HCPs, the ANSI
S12- 12 Working Group has defined ranges of val-ues
that indicate the HCP’s quality as acceptable,
marginal, or unacceptable. These ranges are
shown in table 5. The ranges are slightly different
for the first four years of audiometric testing
( sequential test comparisons 1– 2, 2– 3, and 3– 4)
than for later years of testing. Note that before the
procedures are applied, the population must be
restricted to a group of workers who all have the
same number of audiograms ( ideally, six or more).
73
Table 5
Criterion Ranges for Rating HCP Effectiveness by
Using ADBA Procedures Recommended by the ANSI
S12- 12 Working Group for Evaluation Hearing
Conservation Programs
Advantages and Benefits of ADBA
By using the variability procedures to evaluate the
audiometric data, HCP personnel can detect problems
in the HCP quickly— within one or two years— then act
to correct the deficiencies before many employees devel-op
significant permanent hearing changes. In other
words, the analysis helps HCP personnel to prevent
hearing loss, as illustrated in figure 2.
Simple bar graphs of ADBA results provide useful
feedback for the supervisors and employees in different
departments to show how better HPD utilization pro-duces
lower variability ( see References, item 18). These
concrete results can be effective in motivating employ-ees.
The key individual can use ADBA procedures to
guide policy decisions. If HCP personnel are unsure
whether a particular HPD provides adequate protec-tion,
the ADBA results for employees wearing different
HPDs can be compared. Similar department compar-isons
can show whether required HPD utilization is
74
Recommended percentage values for the % Ws and % BWs ADBA
Procedures ( Sequential Test Comparisons and No Age Corrections)
HCP Rating Over First Four Over Later Test Comparisons
Test Comparisons ( 5– 6, 6– 7, 7– 8, etc.)
( 1– 1, 2– 3, and 3– 4)
% Ws % Ws % Bws
Acceptable < 20 < 17 < 26
Marginal 20 to 30 17 to 27 26 to 40
Unacceptable > 30 > 27 > 40
needed to protect employees in a low- noise department
( see References, item 20).
Figure 2
Using ADBA
Finally, ADBA findings give objective evidence to
demonstrate for management when the budget alloca-tions
for the HCP need to be increased or redistributed
in order to improve protection in departments with
poorer performance. After HCP changes have been
implemented, ADBA results show management the
associated gains, less hearing loss and reduced poten-tial
liability for workers’ compensation claims.
75
➪
{ Noise Environment }
➪
➪
➪
Hearing Loss Begins ADBA Flags HCP STS Confirmed
Service
When the company uses audiometric data base analysis ( ADBA),
problems in the HCP can be detected before employees develop
significant permanent hearing threshold shifts.
Checklist for HCP Evaluation
There is a key individual overseeing all five phas-es
of the HCP.
HCP team members check that all tasks are
accomplished and documented.
HPDs are potentially effective in actual use.
HPD utilization is enforced.
Active communication is maintained among HCP
team members and all personnel up and down the
company hierarchy.
Management holds personnel accountable for their
HCP performance and gives praise or criticism as
appropriate.
Audiometric data base analysis is used to evaluate
the HCP’s effectiveness in preventing on- the- job
hearing loss.
76
References
1. Royster, L. H., Royster, J. D., and Berger, E. H.
Guidelines for developing an effective hearing con-servation
program. Sound and Vibration, volume
16( 5), pages 22– 25, 1982.
2. Royster, L. H., and Royster, J. D. An Overview of
Effective Hearing Conservation Programs. Sound
and Vibration, volume 19( 2), pages 20– 23, 1985.
3. Royster, L. H., and Royster, J. D. Education and
Motivation. In E. H. Berger, W. D. Ward, J. C.
Morrill, and L. H. Royster ( Editors), Noise and
Hearing Conservation Manual, fourth edition.
Akron, Ohio: American Industrial Hygiene
Association, 1986.
4. Berger, E. H., Royster, J. D., Royster, L. H., and
Brus, D. An Earful of Sound Advice about Hearing
Protection. Indianapolis, Indiana: E- A- R Division
of Cabot Corporation, 1988.
5. Royster, L. H., Berger, E. H., and Royster, J. D.
Noise Surveys and Data Analysis. In E. H. Berger,
W. D. Ward, J. C. Morrill, and L. H. Royster
( Editors), Noise and Hearing Conservation
Manual, fourth edition. Akron, Ohio: American
Industrial Hygiene Association, 1986.
6. Bruce, R. D., and Toothman, E. H. Engineering
Controls. In E. H. Berger, W. D. Ward, J. C.
Morrill, and L. H. Royster ( Editors), Noise and
Hearing Conservation Manual, fourth edition.
Akron, Ohio: American Industrial Hygiene
Association, 1986.
7. Purcell, W. E. Materials for Noise and Vibration
Control. Sound and Vibration, volume 14( 7), pages
8– 32, 1980.
77
8. Purcell, W. E. Systems for Noise and Vibration
Control. Sound and Vibration, volume 14( 8), pages
10– 36, 1980.
9. Irwin, J. D., and Graf, E. R. Industrial Noise and
Vibration Control. Englewood Cliffs, New Jersey:
Prentice- Hall, 1979.
10. Wilson, Charles E. Noise Control: Measurement,
Analysis, and Control of Sound and Vibration.
New York: Harper and Row Publisher